diff --git a/doc/release-notes/rl-2511.section.md b/doc/release-notes/rl-2511.section.md
index 314459a6ab97..a8bd8ab82bf0 100644
--- a/doc/release-notes/rl-2511.section.md
+++ b/doc/release-notes/rl-2511.section.md
@@ -26,7 +26,7 @@
 
 - GCC 9, 10, 11, and 12 have been removed, as they have reached end‐of‐life upstream and are no longer supported.
 
-- LLVM 12 and 13 have been removed, as they have reached end‐of‐life upstream and are no longer supported.
+- LLVM 12, 13, and 14 have been removed, as they have reached end‐of‐life upstream and are no longer supported.
 
 - GHCJS 8.10, exposed via `haskell.compiler.ghcjs` and `haskell.compiler.ghcjs810`, has been removed. Downstream users should migrate their projects to the new JavaScript backend of GHC proper which can be used via `pkgsCross.ghcjs` from Nixpkgs. Haskell packaging code, like `haskellPackages.mkDerivation`, `ghcWithPackages` and `hoogleWithPackages`, also no longer supports GHCJS.
 
diff --git a/pkgs/development/compilers/llvm/14/clang/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/14/clang/gnu-install-dirs.patch
deleted file mode 100644
index 57c54e18c37b..000000000000
--- a/pkgs/development/compilers/llvm/14/clang/gnu-install-dirs.patch
+++ /dev/null
@@ -1,50 +0,0 @@
-diff --git a/cmake/modules/AddClang.cmake b/cmake/modules/AddClang.cmake
-index 9bbbfc032b7d..947bd0da865d 100644
---- a/cmake/modules/AddClang.cmake
-+++ b/cmake/modules/AddClang.cmake
-@@ -119,8 +119,8 @@ macro(add_clang_library name)
-         install(TARGETS ${lib}
-           COMPONENT ${lib}
-           ${export_to_clangtargets}
--          LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
--          ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-+          LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}
-+          ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}
-           RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
-
-         if (NOT LLVM_ENABLE_IDE)
-@@ -175,7 +175,7 @@ endmacro()
- macro(add_clang_symlink name dest)
-   add_llvm_tool_symlink(${name} ${dest} ALWAYS_GENERATE)
-   # Always generate install targets
--  llvm_install_symlink(${name} ${dest} ALWAYS_GENERATE)
-+  llvm_install_symlink(${name} ${dest} ${CMAKE_INSTALL_FULL_BINDIR} ALWAYS_GENERATE)
- endmacro()
-
- function(clang_target_link_libraries target type)
-diff --git a/lib/Headers/CMakeLists.txt b/lib/Headers/CMakeLists.txt
-index 078988980c52..14b58614b40a 100644
---- a/lib/Headers/CMakeLists.txt
-+++ b/lib/Headers/CMakeLists.txt
-@@ -234,7 +234,7 @@ set_target_properties(clang-resource-headers PROPERTIES
-   FOLDER "Misc"
-   RUNTIME_OUTPUT_DIRECTORY "${output_dir}")
-
--set(header_install_dir lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
-+set(header_install_dir ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
-
- install(
-   FILES ${files} ${generated_files}
-diff --git a/tools/libclang/CMakeLists.txt b/tools/libclang/CMakeLists.txt
-index 4e0647971ab4..68dd67fcc476 100644
---- a/tools/libclang/CMakeLists.txt
-+++ b/tools/libclang/CMakeLists.txt
-@@ -216,7 +216,7 @@ foreach(PythonVersion ${CLANG_PYTHON_BINDINGS_VERSIONS})
-           COMPONENT
-             libclang-python-bindings
-           DESTINATION
--            "lib${LLVM_LIBDIR_SUFFIX}/python${PythonVersion}/site-packages")
-+            "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/python${PythonVersion}/site-packages")
- endforeach()
- if(NOT LLVM_ENABLE_IDE)
-   add_custom_target(libclang-python-bindings)
diff --git a/pkgs/development/compilers/llvm/14/clang/purity.patch b/pkgs/development/compilers/llvm/14/clang/purity.patch
deleted file mode 100644
index deb230a36c5b..000000000000
--- a/pkgs/development/compilers/llvm/14/clang/purity.patch
+++ /dev/null
@@ -1,28 +0,0 @@
-From 4add81bba40dcec62c4ea4481be8e35ac53e89d8 Mon Sep 17 00:00:00 2001
-From: Will Dietz <w@wdtz.org>
-Date: Thu, 18 May 2017 11:56:12 -0500
-Subject: [PATCH] "purity" patch for 5.0
-
----
- lib/Driver/ToolChains/Gnu.cpp | 7 -------
- 1 file changed, 7 deletions(-)
-
-diff --git a/lib/Driver/ToolChains/Gnu.cpp b/lib/Driver/ToolChains/Gnu.cpp
-index fe3c0191bb..c6a482bece 100644
---- a/lib/Driver/ToolChains/Gnu.cpp
-+++ b/lib/Driver/ToolChains/Gnu.cpp
-@@ -487,12 +487,6 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
-   if (!IsStatic) {
-     if (Args.hasArg(options::OPT_rdynamic))
-       CmdArgs.push_back("-export-dynamic");
--
--    if (!Args.hasArg(options::OPT_shared) && !IsStaticPIE) {
--      CmdArgs.push_back("-dynamic-linker");
--      CmdArgs.push_back(Args.MakeArgString(Twine(D.DyldPrefix) +
--                                           ToolChain.getDynamicLinker(Args)));
--    }
-   }
- 
-   CmdArgs.push_back("-o");
--- 
-2.11.0
diff --git a/pkgs/development/compilers/llvm/14/compiler-rt/X86-support-extension.patch b/pkgs/development/compilers/llvm/14/compiler-rt/X86-support-extension.patch
deleted file mode 100644
index 66742e5b1498..000000000000
--- a/pkgs/development/compilers/llvm/14/compiler-rt/X86-support-extension.patch
+++ /dev/null
@@ -1,21 +0,0 @@
-diff --git a/lib/builtins/CMakeLists.txt b/lib/builtins/CMakeLists.txt
-index 3a66dd9c3fb..7efc85d9f9f 100644
---- a/lib/builtins/CMakeLists.txt
-+++ b/lib/builtins/CMakeLists.txt
-@@ -345,4 +345,8 @@ if (NOT MSVC)
- 
-+  set(i486_SOURCES ${i386_SOURCES})
-+  set(i586_SOURCES ${i386_SOURCES})
-+  set(i686_SOURCES ${i386_SOURCES})
-+
-   if (WIN32)
-     set(i386_SOURCES
-       ${i386_SOURCES}
-@@ -608,6 +612,7 @@ else ()
-   endif()
- 
-   foreach (arch ${BUILTIN_SUPPORTED_ARCH})
-+      message("arch: ${arch}")
-     if (CAN_TARGET_${arch})
-       # For ARM archs, exclude any VFP builtins if VFP is not supported
-       if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7m|armv7em)$")
diff --git a/pkgs/development/compilers/llvm/14/compiler-rt/armv6-scudo-libatomic.patch b/pkgs/development/compilers/llvm/14/compiler-rt/armv6-scudo-libatomic.patch
deleted file mode 100644
index 13b67eb2a41c..000000000000
--- a/pkgs/development/compilers/llvm/14/compiler-rt/armv6-scudo-libatomic.patch
+++ /dev/null
@@ -1,65 +0,0 @@
-From a56bb19a9dc303a50ef12d83cd24c2395bf81076 Mon Sep 17 00:00:00 2001
-From: Ben Wolsieffer <benwolsieffer@gmail.com>
-Date: Wed, 7 Dec 2022 21:25:46 -0500
-Subject: [PATCH] [scudo][standalone] Use CheckAtomic to decide to link to
- libatomic
-
-Standalone scudo uses the atomic operation builtin functions, which require
-linking to libatomic on some platforms. Currently, this is done in an ad-hoc
-manner. MIPS platforms always link to libatomic, and the tests are always linked
-to it as well. libatomic is required on base ARMv6 (but not ARMv6K), but it is
-currently not linked, causing the build to fail.
-
-This patch replaces this ad-hoc logic with the CheckAtomic CMake module already
-used in other parts of LLVM. The CheckAtomic module checks whether std::atomic
-requires libatomic, which is not strictly the same as checking the atomic
-builtins, but should have the same results as far as I know. If this is
-problematic, a custom version of CheckAtomic could be used to specifically test
-the builtins.
----
- compiler-rt/lib/scudo/standalone/CMakeLists.txt       | 7 +++++++
- compiler-rt/lib/scudo/standalone/tests/CMakeLists.txt | 4 +---
- 2 files changed, 8 insertions(+), 3 deletions(-)
-
-diff --git a/lib/scudo/standalone/CMakeLists.txt b/lib/scudo/standalone/CMakeLists.txt
-index ae5c354768c8..eb27374ca520 100644
---- a/lib/scudo/standalone/CMakeLists.txt
-+++ b/lib/scudo/standalone/CMakeLists.txt
-@@ -1,5 +1,8 @@
- add_compiler_rt_component(scudo_standalone)
- 
-+include(DetermineGCCCompatible)
-+include(CheckAtomic)
-+
- include_directories(../.. include)
- 
- set(SCUDO_CFLAGS)
-@@ -34,6 +37,10 @@ list(APPEND SCUDO_LINK_FLAGS -Wl,-z,defs,-z,now,-z,relro)
- 
- list(APPEND SCUDO_LINK_FLAGS -ffunction-sections -fdata-sections -Wl,--gc-sections)
- 
-+if(HAVE_CXX_ATOMICS_WITH_LIB OR HAVE_CXX_ATOMICS64_WITH_LIB)
-+  list(APPEND SCUDO_LINK_FLAGS -latomic)
-+endif()
-+
- # We don't use the C++ standard library, so avoid including it by mistake.
- append_list_if(COMPILER_RT_HAS_NOSTDLIBXX_FLAG -nostdlib++ SCUDO_LINK_FLAGS)
- 
-diff --git a/lib/scudo/standalone/tests/CMakeLists.txt b/lib/scudo/standalone/tests/CMakeLists.txt
-index 6d0936cbb5c1..70a5a7e959c1 100644
---- a/lib/scudo/standalone/tests/CMakeLists.txt
-+++ b/lib/scudo/standalone/tests/CMakeLists.txt
-@@ -38,9 +38,7 @@ set(LINK_FLAGS
-   ${SANITIZER_TEST_CXX_LIBRARIES}
-   )
- list(APPEND LINK_FLAGS -pthread)
--# Linking against libatomic is required with some compilers
--check_library_exists(atomic __atomic_load_8 "" COMPILER_RT_HAS_LIBATOMIC)
--if (COMPILER_RT_HAS_LIBATOMIC)
-+if(HAVE_CXX_ATOMICS_WITH_LIB OR HAVE_CXX_ATOMICS64_WITH_LIB)
-   list(APPEND LINK_FLAGS -latomic)
- endif()
- 
--- 
-2.38.1
-
diff --git a/pkgs/development/compilers/llvm/14/compiler-rt/armv7l.patch b/pkgs/development/compilers/llvm/14/compiler-rt/armv7l.patch
deleted file mode 100644
index 6818684e6a71..000000000000
--- a/pkgs/development/compilers/llvm/14/compiler-rt/armv7l.patch
+++ /dev/null
@@ -1,31 +0,0 @@
-diff -ur compiler-rt-10.0.0.src/cmake/builtin-config-ix.cmake compiler-rt-10.0.0.src-patched/cmake/builtin-config-ix.cmake
---- compiler-rt-10.0.0.src/cmake/builtin-config-ix.cmake	2020-03-24 00:01:02.000000000 +0900
-+++ compiler-rt-10.0.0.src-patched/cmake/builtin-config-ix.cmake	2020-05-10 03:42:00.883450706 +0900
-@@ -37,6 +37,6 @@
- 
- set(ARM64 aarch64)
--set(ARM32 arm armhf armv6m armv7m armv7em armv7 armv7s armv7k armv8m.main armv8.1m.main)
-+set(ARM32 arm armhf armv6m armv7m armv7em armv7 armv7s armv7k armv7l armv8m.main armv8.1m.main)
- set(HEXAGON hexagon)
- set(X86 i386)
- set(X86_64 x86_64)
-diff -ur compiler-rt-10.0.0.src/lib/builtins/CMakeLists.txt compiler-rt-10.0.0.src-patched/lib/builtins/CMakeLists.txt
---- compiler-rt-10.0.0.src/lib/builtins/CMakeLists.txt	2020-03-24 00:01:02.000000000 +0900
-+++ compiler-rt-10.0.0.src-patched/lib/builtins/CMakeLists.txt	2020-05-10 03:44:49.468579650 +0900
-@@ -555,6 +555,7 @@
- set(armv7_SOURCES ${arm_SOURCES})
- set(armv7s_SOURCES ${arm_SOURCES})
- set(armv7k_SOURCES ${arm_SOURCES})
-+set(armv7l_SOURCES ${arm_SOURCES})
- set(arm64_SOURCES ${aarch64_SOURCES})
- 
- # macho_embedded archs
-@@ -705,7 +705,7 @@
-   foreach (arch ${BUILTIN_SUPPORTED_ARCH})
-     if (CAN_TARGET_${arch})
-       # For ARM archs, exclude any VFP builtins if VFP is not supported
--      if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7m|armv7em|armv8m.main|armv8.1m.main)$")
-+      if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7l|armv7m|armv7em|armv8m.main|armv8.1m.main)$")
-         string(REPLACE ";" " " _TARGET_${arch}_CFLAGS "${TARGET_${arch}_CFLAGS}")
-         check_compile_definition(__VFP_FP__ "${CMAKE_C_FLAGS} ${_TARGET_${arch}_CFLAGS}" COMPILER_RT_HAS_${arch}_VFP)
-         if(NOT COMPILER_RT_HAS_${arch}_VFP)
diff --git a/pkgs/development/compilers/llvm/14/compiler-rt/codesign.patch b/pkgs/development/compilers/llvm/14/compiler-rt/codesign.patch
deleted file mode 100644
index 065959d14d46..000000000000
--- a/pkgs/development/compilers/llvm/14/compiler-rt/codesign.patch
+++ /dev/null
@@ -1,33 +0,0 @@
-From 3dec5f3475a26aeb4678627795c4b67c6b7b4785 Mon Sep 17 00:00:00 2001
-From: Will Dietz <w@wdtz.org>
-Date: Tue, 19 Sep 2017 13:13:06 -0500
-Subject: [PATCH] remove codesign use on Apple, disable ios sim testing that
- needs it
-
----
- cmake/Modules/AddCompilerRT.cmake |  8 ------
- test/asan/CMakeLists.txt          | 52 ---------------------------------------
- test/tsan/CMakeLists.txt          | 47 -----------------------------------
- 3 files changed, 107 deletions(-)
-
-diff --git a/cmake/Modules/AddCompilerRT.cmake b/cmake/Modules/AddCompilerRT.cmake
-index bc69ec95c419..9f100fdcec2f 100644
---- a/cmake/Modules/AddCompilerRT.cmake
-+++ b/cmake/Modules/AddCompilerRT.cmake
-@@ -366,14 +366,6 @@ function(add_compiler_rt_runtime name type)
-         set_target_properties(${libname} PROPERTIES IMPORT_PREFIX "")
-         set_target_properties(${libname} PROPERTIES IMPORT_SUFFIX ".lib")
-       endif()
--      if(APPLE)
--        # Ad-hoc sign the dylibs
--        add_custom_command(TARGET ${libname}
--          POST_BUILD  
--          COMMAND codesign --sign - $<TARGET_FILE:${libname}>
--          WORKING_DIRECTORY ${COMPILER_RT_OUTPUT_LIBRARY_DIR}
--        )
--      endif()
-     endif()
- 
-     set(parent_target_arg)
-2.14.1
-
diff --git a/pkgs/development/compilers/llvm/14/compiler-rt/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/14/compiler-rt/gnu-install-dirs.patch
deleted file mode 100644
index 55837bd8e45b..000000000000
--- a/pkgs/development/compilers/llvm/14/compiler-rt/gnu-install-dirs.patch
+++ /dev/null
@@ -1,42 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
-index 3a41aa43e406..f000cee6eae0 100644
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -5,6 +5,8 @@
-
- cmake_minimum_required(VERSION 3.13.4)
-
-+include(GNUInstallDirs)
-+
- # Check if compiler-rt is built as a standalone project.
- if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR COMPILER_RT_STANDALONE_BUILD)
-   project(CompilerRT C CXX ASM)
-diff --git a/cmake/base-config-ix.cmake b/cmake/base-config-ix.cmake
-index d7b0124f3546..3e111146df4d 100644
---- a/cmake/base-config-ix.cmake
-+++ b/cmake/base-config-ix.cmake
-@@ -67,7 +67,7 @@ if (LLVM_TREE_AVAILABLE)
- else()
-     # Take output dir and install path from the user.
-   set(COMPILER_RT_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR} CACHE PATH
--    "Path where built compiler-rt libraries should be stored.")
-+    "Path where built compiler-rt build artifacts should be stored.")
-   set(COMPILER_RT_EXEC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/bin CACHE PATH
-     "Path where built compiler-rt executables should be stored.")
-   set(COMPILER_RT_INSTALL_PATH "" CACHE PATH
-@@ -99,13 +99,13 @@ endif()
- if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
-   set(COMPILER_RT_OUTPUT_LIBRARY_DIR
-     ${COMPILER_RT_OUTPUT_DIR}/lib)
--  extend_path(default_install_path "${COMPILER_RT_INSTALL_PATH}" lib)
-+  extend_path(default_install_path "${COMPILER_RT_INSTALL_PATH}" "${CMAKE_INSTALL_LIBDIR}")
-   set(COMPILER_RT_INSTALL_LIBRARY_DIR "${default_install_path}" CACHE PATH
-     "Path where built compiler-rt libraries should be installed.")
- else(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
-   set(COMPILER_RT_OUTPUT_LIBRARY_DIR
-     ${COMPILER_RT_OUTPUT_DIR}/lib/${COMPILER_RT_OS_DIR})
--  extend_path(default_install_path "${COMPILER_RT_INSTALL_PATH}" "lib/${COMPILER_RT_OS_DIR}")
-+  extend_path(default_install_path "${COMPILER_RT_INSTALL_PATH}" "${CMAKE_INSTALL_LIBDIR}/${COMPILER_RT_OS_DIR}")
-   set(COMPILER_RT_INSTALL_LIBRARY_DIR "${default_install_path}" CACHE PATH
-     "Path where built compiler-rt libraries should be installed.")
- endif()
diff --git a/pkgs/development/compilers/llvm/14/libunwind/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/14/libunwind/gnu-install-dirs.patch
deleted file mode 100644
index 3fce8bf90343..000000000000
--- a/pkgs/development/compilers/llvm/14/libunwind/gnu-install-dirs.patch
+++ /dev/null
@@ -1,21 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -147,7 +147,7 @@ set(LIBUNWIND_INSTALL_RUNTIME_DIR "${CMAKE_INSTALL_BINDIR}" CACHE PATH
- 
- if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
-   set(LIBUNWIND_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
--  set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE} CACHE PATH
-+  set(LIBUNWIND_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE} CACHE PATH
-       "Path where built libunwind libraries should be installed.")
-   if(LIBCXX_LIBDIR_SUBDIR)
-     string(APPEND LIBUNWIND_LIBRARY_DIR /${LIBUNWIND_LIBDIR_SUBDIR})
-@@ -159,7 +159,7 @@ else()
-   else()
-     set(LIBUNWIND_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBUNWIND_LIBDIR_SUFFIX})
-   endif()
--  set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LIBUNWIND_LIBDIR_SUFFIX} CACHE PATH
-+  set(LIBUNWIND_INSTALL_LIBRARY_DIR ${CMAKE_INSTALL_LIBDIR}${LIBUNWIND_LIBDIR_SUFFIX} CACHE PATH
-       "Path where built libunwind libraries should be installed.")
- endif()
- 
diff --git a/pkgs/development/compilers/llvm/14/lld/fix-root-src-dir.patch b/pkgs/development/compilers/llvm/14/lld/fix-root-src-dir.patch
deleted file mode 100644
index 38fb965b472a..000000000000
--- a/pkgs/development/compilers/llvm/14/lld/fix-root-src-dir.patch
+++ /dev/null
@@ -1,13 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
-index 9bcc135665d0..d38679ed41e9 100644
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -74,7 +74,7 @@ if(LLD_BUILT_STANDALONE)
-
-   set(LLVM_MAIN_INCLUDE_DIR "${MAIN_INCLUDE_DIR}" CACHE PATH "Path to llvm/include")
-   set(LLVM_BINARY_DIR "${LLVM_OBJ_ROOT}" CACHE PATH "Path to LLVM build tree")
--  set(LLVM_MAIN_SRC_DIR "${MAIN_SRC_DIR}" CACHE PATH "Path to LLVM source tree")
-+  set(LLVM_MAIN_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../llvm" CACHE PATH "Path to LLVM source tree")
-
-   find_program(LLVM_TABLEGEN_EXE "llvm-tblgen" ${LLVM_TOOLS_BINARY_DIR}
-     NO_DEFAULT_PATH)
diff --git a/pkgs/development/compilers/llvm/14/lld/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/14/lld/gnu-install-dirs.patch
deleted file mode 100644
index 89a5822df49c..000000000000
--- a/pkgs/development/compilers/llvm/14/lld/gnu-install-dirs.patch
+++ /dev/null
@@ -1,22 +0,0 @@
-diff --git a/cmake/modules/AddLLD.cmake b/cmake/modules/AddLLD.cmake
-index dd2898ce6236..ebbea040ff54 100644
---- a/cmake/modules/AddLLD.cmake
-+++ b/cmake/modules/AddLLD.cmake
-@@ -18,8 +18,8 @@ macro(add_lld_library name)
-     install(TARGETS ${name}
-       COMPONENT ${name}
-       ${export_to_lldtargets}
--      LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
--      ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}"
-+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}"
-       RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
- 
-     if (${ARG_SHARED} AND NOT CMAKE_CONFIGURATION_TYPES)
-@@ -62,5 +62,5 @@ endmacro()
- macro(add_lld_symlink name dest)
-   add_llvm_tool_symlink(${name} ${dest} ALWAYS_GENERATE)
-   # Always generate install targets
--  llvm_install_symlink(${name} ${dest} ALWAYS_GENERATE)
-+  llvm_install_symlink(${name} ${dest} ${CMAKE_INSTALL_FULL_BINDIR} ALWAYS_GENERATE)
- endmacro()
diff --git a/pkgs/development/compilers/llvm/14/lldb/procfs.patch b/pkgs/development/compilers/llvm/14/lldb/procfs.patch
deleted file mode 100644
index b075dbaeee0a..000000000000
--- a/pkgs/development/compilers/llvm/14/lldb/procfs.patch
+++ /dev/null
@@ -1,31 +0,0 @@
---- a/source/Plugins/Process/Linux/Procfs.h
-+++ b/source/Plugins/Process/Linux/Procfs.h
-@@ -11,21 +11,12 @@
- // sys/procfs.h on Android/Linux for all supported architectures.
- 
- #include <sys/ptrace.h>
-+#include <asm/ptrace.h>
- 
--#ifdef __ANDROID__
--#if defined(__arm64__) || defined(__aarch64__)
--typedef unsigned long elf_greg_t;
--typedef elf_greg_t
--    elf_gregset_t[(sizeof(struct user_pt_regs) / sizeof(elf_greg_t))];
--typedef struct user_fpsimd_state elf_fpregset_t;
--#ifndef NT_FPREGSET
--#define NT_FPREGSET NT_PRFPREG
--#endif // NT_FPREGSET
--#elif defined(__mips__)
--#ifndef NT_FPREGSET
--#define NT_FPREGSET NT_PRFPREG
--#endif // NT_FPREGSET
--#endif
--#else // __ANDROID__
-+#if !defined(__GLIBC__) && defined(__powerpc__)
-+#define pt_regs musl_pt_regs
-+#include <sys/procfs.h>
-+#undef pt_regs
-+#else
- #include <sys/procfs.h>
--#endif // __ANDROID__
-+#endif
diff --git a/pkgs/development/compilers/llvm/14/llvm/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/14/llvm/gnu-install-dirs.patch
deleted file mode 100644
index 55862ab39304..000000000000
--- a/pkgs/development/compilers/llvm/14/llvm/gnu-install-dirs.patch
+++ /dev/null
@@ -1,220 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
-index fec956091cd5..5a766f5c5d7c 100644
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -303,6 +303,9 @@ set(LLVM_EXAMPLES_INSTALL_DIR "examples" CACHE STRING
-     "Path for examples subdirectory (enabled by LLVM_BUILD_EXAMPLES=ON) (defaults to 'examples')")
- mark_as_advanced(LLVM_EXAMPLES_INSTALL_DIR)
- 
-+set(LLVM_INSTALL_CMAKE_DIR "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/cmake/llvm" CACHE STRING
-+	"Path for CMake subdirectory (defaults to lib/cmake/llvm)" )
-+
- # They are used as destination of target generators.
- set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)
- set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
-diff --git a/cmake/modules/AddLLVM.cmake b/cmake/modules/AddLLVM.cmake
-index fed1fec7d72e..4baed19b9e98 100644
---- a/cmake/modules/AddLLVM.cmake
-+++ b/cmake/modules/AddLLVM.cmake
-@@ -838,8 +838,8 @@ macro(add_llvm_library name)
-       get_target_export_arg(${name} LLVM export_to_llvmexports ${umbrella})
-       install(TARGETS ${name}
-               ${export_to_llvmexports}
--              LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
--              ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
-+              LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" COMPONENT ${name}
-+              ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" COMPONENT ${name}
-               RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" COMPONENT ${name})
- 
-       if (NOT LLVM_ENABLE_IDE)
-@@ -1056,7 +1056,7 @@ function(process_llvm_pass_plugins)
-           "set(LLVM_STATIC_EXTENSIONS ${LLVM_STATIC_EXTENSIONS})")
-       install(FILES
-           ${llvm_cmake_builddir}/LLVMConfigExtensions.cmake
--          DESTINATION ${LLVM_INSTALL_PACKAGE_DIR}
-+          DESTINATION ${LLVM_INSTALL_CMAKE_DIR}
-           COMPONENT cmake-exports)
- 
-       set(ExtensionDef "${LLVM_BINARY_DIR}/include/llvm/Support/Extension.def")
-@@ -1902,7 +1902,7 @@ function(llvm_install_library_symlink name dest type)
-   set(full_name ${CMAKE_${type}_LIBRARY_PREFIX}${name}${CMAKE_${type}_LIBRARY_SUFFIX})
-   set(full_dest ${CMAKE_${type}_LIBRARY_PREFIX}${dest}${CMAKE_${type}_LIBRARY_SUFFIX})
- 
--  set(output_dir lib${LLVM_LIBDIR_SUFFIX})
-+  set(output_dir ${CMAKE_INSTALL_FULL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
-   if(WIN32 AND "${type}" STREQUAL "SHARED")
-     set(output_dir bin)
-   endif()
-@@ -1913,7 +1913,7 @@ function(llvm_install_library_symlink name dest type)
- 
- endfunction()
- 
--function(llvm_install_symlink name dest)
-+function(llvm_install_symlink name dest output_dir)
-   cmake_parse_arguments(ARG "ALWAYS_GENERATE" "COMPONENT" "" ${ARGN})
-   foreach(path ${CMAKE_MODULE_PATH})
-     if(EXISTS ${path}/LLVMInstallSymlink.cmake)
-@@ -1936,7 +1936,7 @@ function(llvm_install_symlink name dest)
-   set(full_dest ${dest}${CMAKE_EXECUTABLE_SUFFIX})
- 
-   install(SCRIPT ${INSTALL_SYMLINK}
--          CODE "install_symlink(${full_name} ${full_dest} ${LLVM_TOOLS_INSTALL_DIR})"
-+          CODE "install_symlink(${full_name} ${full_dest} ${output_dir})"
-           COMPONENT ${component})
- 
-   if (NOT LLVM_ENABLE_IDE AND NOT ARG_ALWAYS_GENERATE)
-@@ -2019,7 +2019,8 @@ function(add_llvm_tool_symlink link_name target)
-     endif()
- 
-     if ((TOOL_IS_TOOLCHAIN OR NOT LLVM_INSTALL_TOOLCHAIN_ONLY) AND LLVM_BUILD_TOOLS)
--      llvm_install_symlink(${link_name} ${target})
-+      GNUInstallDirs_get_absolute_install_dir(output_dir LLVM_TOOLS_INSTALL_DIR)
-+      llvm_install_symlink(${link_name} ${target} ${output_dir})
-     endif()
-   endif()
- endfunction()
-@@ -2148,9 +2149,9 @@ function(llvm_setup_rpath name)
-     # Since BUILD_SHARED_LIBS is only recommended for use by developers,
-     # hardcode the rpath to build/install lib dir first in this mode.
-     # FIXME: update this when there is better solution.
--    set(_install_rpath "${LLVM_LIBRARY_OUTPUT_INTDIR}" "${CMAKE_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-+    set(_install_rpath "${LLVM_LIBRARY_OUTPUT_INTDIR}" "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-   elseif(UNIX)
--    set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-+    set(_install_rpath "\$ORIGIN/../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-     if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
-       set_property(TARGET ${name} APPEND_STRING PROPERTY
-                    LINK_FLAGS " -Wl,-z,origin ")
-diff --git a/cmake/modules/AddOCaml.cmake b/cmake/modules/AddOCaml.cmake
-index 891c9e6d618c..8d963f3b0069 100644
---- a/cmake/modules/AddOCaml.cmake
-+++ b/cmake/modules/AddOCaml.cmake
-@@ -147,9 +147,9 @@ function(add_ocaml_library name)
-   endforeach()
- 
-   if( APPLE )
--    set(ocaml_rpath "@executable_path/../../../lib${LLVM_LIBDIR_SUFFIX}")
-+    set(ocaml_rpath "@executable_path/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
-   elseif( UNIX )
--    set(ocaml_rpath "\\$ORIGIN/../../../lib${LLVM_LIBDIR_SUFFIX}")
-+    set(ocaml_rpath "\\$ORIGIN/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
-   endif()
-   list(APPEND ocaml_flags "-ldopt" "-Wl,-rpath,${ocaml_rpath}")
- 
-diff --git a/cmake/modules/CMakeLists.txt b/cmake/modules/CMakeLists.txt
-index cea0c1df0a14..eedcd9450312 100644
---- a/cmake/modules/CMakeLists.txt
-+++ b/cmake/modules/CMakeLists.txt
-@@ -2,7 +2,7 @@ include(ExtendPath)
- include(LLVMDistributionSupport)
- include(FindPrefixFromConfig)
- 
--set(LLVM_INSTALL_PACKAGE_DIR lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm)
-+set(LLVM_INSTALL_PACKAGE_DIR ${LLVM_INSTALL_CMAKE_DIR} CACHE STRING "Path for CMake subdirectory (defaults to 'cmake/llvm')")
- set(llvm_cmake_builddir "${LLVM_BINARY_DIR}/${LLVM_INSTALL_PACKAGE_DIR}")
- 
- # First for users who use an installed LLVM, create the LLVMExports.cmake file.
-@@ -122,7 +122,7 @@ set(LLVM_CONFIG_INCLUDE_DIRS
-   )
- list(REMOVE_DUPLICATES LLVM_CONFIG_INCLUDE_DIRS)
- 
--extend_path(LLVM_CONFIG_LIBRARY_DIR "\${LLVM_INSTALL_PREFIX}" "lib\${LLVM_LIBDIR_SUFFIX}")
-+extend_path(LLVM_CONFIG_LIBRARY_DIR "\${LLVM_INSTALL_PREFIX}" "${CMAKE_INSTALL_LIBDIR}\${LLVM_LIBDIR_SUFFIX}")
- set(LLVM_CONFIG_LIBRARY_DIRS
-   "${LLVM_CONFIG_LIBRARY_DIR}"
-   # FIXME: Should there be other entries here?
-diff --git a/cmake/modules/LLVMInstallSymlink.cmake b/cmake/modules/LLVMInstallSymlink.cmake
-index b5c35f706cb7..9261ab797de6 100644
---- a/cmake/modules/LLVMInstallSymlink.cmake
-+++ b/cmake/modules/LLVMInstallSymlink.cmake
-@@ -6,7 +6,7 @@ include(GNUInstallDirs)
- 
- function(install_symlink name target outdir)
-   set(DESTDIR $ENV{DESTDIR})
--  set(bindir "${DESTDIR}${CMAKE_INSTALL_PREFIX}/${outdir}")
-+  set(bindir "${DESTDIR}${outdir}/")
- 
-   message(STATUS "Creating ${name}")
- 
-diff --git a/docs/CMake.rst b/docs/CMake.rst
-index 044ec8a4d39d..504d0eac3ade 100644
---- a/docs/CMake.rst
-+++ b/docs/CMake.rst
-@@ -224,7 +224,7 @@ description is in `LLVM-related variables`_ below.
- **LLVM_LIBDIR_SUFFIX**:STRING
-   Extra suffix to append to the directory where libraries are to be
-   installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
--  to install libraries to ``/usr/lib64``.
-+  to install libraries to ``/usr/lib64``. See also ``CMAKE_INSTALL_LIBDIR``.
- 
- **LLVM_PARALLEL_{COMPILE,LINK}_JOBS**:STRING
-   Building the llvm toolchain can use a lot of resources, particularly
-@@ -910,9 +910,11 @@ the ``cmake`` command or by setting it directly in ``ccmake`` or ``cmake-gui``).
- 
- This file is available in two different locations.
- 
--* ``<INSTALL_PREFIX>/lib/cmake/llvm/LLVMConfig.cmake`` where
--  ``<INSTALL_PREFIX>`` is the install prefix of an installed version of LLVM.
--  On Linux typically this is ``/usr/lib/cmake/llvm/LLVMConfig.cmake``.
-+* ``<LLVM_INSTALL_PACKAGE_DIR>LLVMConfig.cmake`` where
-+  ``<LLVM_INSTALL_PACKAGE_DIR>`` is the location where LLVM CMake modules are
-+  installed as part of an installed version of LLVM. This is typically
-+  ``cmake/llvm/`` within the lib directory. On Linux, this is typically
-+  ``/usr/lib/cmake/llvm/LLVMConfig.cmake``.
- 
- * ``<LLVM_BUILD_ROOT>/lib/cmake/llvm/LLVMConfig.cmake`` where
-   ``<LLVM_BUILD_ROOT>`` is the root of the LLVM build tree. **Note: this is only
-diff --git a/include/llvm/CMakeLists.txt b/include/llvm/CMakeLists.txt
-index b46319f24fc8..2feabd1954e4 100644
---- a/include/llvm/CMakeLists.txt
-+++ b/include/llvm/CMakeLists.txt
-@@ -5,5 +5,5 @@ add_subdirectory(Frontend)
- # If we're doing an out-of-tree build, copy a module map for generated
- # header files into the build area.
- if (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
--  configure_file(module.modulemap.build module.modulemap COPYONLY)
-+  configure_file(module.modulemap.build ${LLVM_INCLUDE_DIR}/module.modulemap COPYONLY)
- endif (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
-diff --git a/tools/llvm-config/BuildVariables.inc.in b/tools/llvm-config/BuildVariables.inc.in
-index abbb8a450da6..70c497be12f5 100644
---- a/tools/llvm-config/BuildVariables.inc.in
-+++ b/tools/llvm-config/BuildVariables.inc.in
-@@ -23,7 +23,10 @@
- #define LLVM_CXXFLAGS "@LLVM_CXXFLAGS@"
- #define LLVM_BUILDMODE "@LLVM_BUILDMODE@"
- #define LLVM_LIBDIR_SUFFIX "@LLVM_LIBDIR_SUFFIX@"
-+#define LLVM_INSTALL_BINDIR "@CMAKE_INSTALL_BINDIR@"
-+#define LLVM_INSTALL_LIBDIR "@CMAKE_INSTALL_LIBDIR@"
- #define LLVM_INSTALL_INCLUDEDIR "@CMAKE_INSTALL_INCLUDEDIR@"
-+#define LLVM_INSTALL_CMAKEDIR "@LLVM_INSTALL_CMAKE_DIR@"
- #define LLVM_TARGETS_BUILT "@LLVM_TARGETS_BUILT@"
- #define LLVM_SYSTEM_LIBS "@LLVM_SYSTEM_LIBS@"
- #define LLVM_BUILD_SYSTEM "@LLVM_BUILD_SYSTEM@"
-diff --git a/tools/llvm-config/llvm-config.cpp b/tools/llvm-config/llvm-config.cpp
-index 8ed88f33ead4..5e7184bab90d 100644
---- a/tools/llvm-config/llvm-config.cpp
-+++ b/tools/llvm-config/llvm-config.cpp
-@@ -363,12 +363,20 @@ int main(int argc, char **argv) {
-       ActiveIncludeDir = std::string(Path.str());
-     }
-     {
--      SmallString<256> Path(LLVM_TOOLS_INSTALL_DIR);
-+      SmallString<256> Path(LLVM_INSTALL_BINDIR);
-       sys::fs::make_absolute(ActivePrefix, Path);
-       ActiveBinDir = std::string(Path.str());
-     }
--    ActiveLibDir = ActivePrefix + "/lib" + LLVM_LIBDIR_SUFFIX;
--    ActiveCMakeDir = ActiveLibDir + "/cmake/llvm";
-+    {
-+      SmallString<256> Path(LLVM_INSTALL_LIBDIR LLVM_LIBDIR_SUFFIX);
-+      sys::fs::make_absolute(ActivePrefix, Path);
-+      ActiveLibDir = std::string(Path.str());
-+    }
-+    {
-+      SmallString<256> Path(LLVM_INSTALL_CMAKEDIR);
-+      sys::fs::make_absolute(ActivePrefix, Path);
-+      ActiveCMakeDir = std::string(Path.str());
-+    }
-     ActiveIncludeOption = "-I" + ActiveIncludeDir;
-   }
- 
diff --git a/pkgs/development/compilers/llvm/14/openmp/gnu-install-dirs.patch b/pkgs/development/compilers/llvm/14/openmp/gnu-install-dirs.patch
deleted file mode 100644
index e85fde46ca3f..000000000000
--- a/pkgs/development/compilers/llvm/14/openmp/gnu-install-dirs.patch
+++ /dev/null
@@ -1,45 +0,0 @@
-diff --git a/CMakeLists.txt b/CMakeLists.txt
---- a/CMakeLists.txt
-+++ b/CMakeLists.txt
-@@ -24,7 +24,7 @@ if (OPENMP_STANDALONE_BUILD)
-   set(OPENMP_LIBDIR_SUFFIX "" CACHE STRING
-     "Suffix of lib installation directory, e.g. 64 => lib64")
-   # Do not use OPENMP_LIBDIR_SUFFIX directly, use OPENMP_INSTALL_LIBDIR.
--  set(OPENMP_INSTALL_LIBDIR "lib${OPENMP_LIBDIR_SUFFIX}")
-+  set(OPENMP_INSTALL_LIBDIR "${CMAKE_INSTALL_LIBDIR}${OPENMP_LIBDIR_SUFFIX}")
- 
-   # Group test settings.
-   set(OPENMP_TEST_C_COMPILER ${CMAKE_C_COMPILER} CACHE STRING
-@@ -35,7 +35,7 @@ if (OPENMP_STANDALONE_BUILD)
- else()
-   set(OPENMP_ENABLE_WERROR ${LLVM_ENABLE_WERROR})
-   # If building in tree, we honor the same install suffix LLVM uses.
--  set(OPENMP_INSTALL_LIBDIR "lib${LLVM_LIBDIR_SUFFIX}")
-+  set(OPENMP_INSTALL_LIBDIR "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
- 
-   if (NOT MSVC)
-     set(OPENMP_TEST_C_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang)
-diff --git a/libomptarget/plugins/amdgpu/CMakeLists.txt b/libomptarget/plugins/amdgpu/CMakeLists.txt
---- a/libomptarget/plugins/amdgpu/CMakeLists.txt
-+++ b/libomptarget/plugins/amdgpu/CMakeLists.txt
-@@ -74,7 +74,7 @@ add_library(omptarget.rtl.amdgpu SHARED
- 
- # Install plugin under the lib destination folder.
- # When we build for debug, OPENMP_LIBDIR_SUFFIX get set to -debug
--install(TARGETS omptarget.rtl.amdgpu LIBRARY DESTINATION "lib${OPENMP_LIBDIR_SUFFIX}")
-+install(TARGETS omptarget.rtl.amdgpu LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}${OPENMP_LIBDIR_SUFFIX}")
- set_property(TARGET omptarget.rtl.amdgpu PROPERTY INSTALL_RPATH_USE_LINK_PATH ON)
- 
- if(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
-diff --git a/libomptarget/plugins/ve/CMakeLists.txt b/libomptarget/plugins/ve/CMakeLists.txt
---- a/libomptarget/plugins/ve/CMakeLists.txt
-+++ b/libomptarget/plugins/ve/CMakeLists.txt
-@@ -32,7 +32,7 @@ if(${LIBOMPTARGET_DEP_VEO_FOUND})
- 
-   # Install plugin under the lib destination folder.
-   install(TARGETS "omptarget.rtl.${tmachine_libname}"
--    LIBRARY DESTINATION lib${OPENMP_LIBDIR_SUFFIX})
-+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}${OPENMP_LIBDIR_SUFFIX})
- 
-   target_link_libraries(
-     "omptarget.rtl.${tmachine_libname}"
diff --git a/pkgs/development/compilers/llvm/14/compiler-rt/darwin-targetconditionals.patch b/pkgs/development/compilers/llvm/15/compiler-rt/darwin-targetconditionals.patch
similarity index 100%
rename from pkgs/development/compilers/llvm/14/compiler-rt/darwin-targetconditionals.patch
rename to pkgs/development/compilers/llvm/15/compiler-rt/darwin-targetconditionals.patch
diff --git a/pkgs/development/compilers/llvm/14/compiler-rt/normalize-var.patch b/pkgs/development/compilers/llvm/15/compiler-rt/normalize-var.patch
similarity index 100%
rename from pkgs/development/compilers/llvm/14/compiler-rt/normalize-var.patch
rename to pkgs/development/compilers/llvm/15/compiler-rt/normalize-var.patch
diff --git a/pkgs/development/compilers/llvm/14/lldb/resource-dir.patch b/pkgs/development/compilers/llvm/15/lldb/resource-dir.patch
similarity index 100%
rename from pkgs/development/compilers/llvm/14/lldb/resource-dir.patch
rename to pkgs/development/compilers/llvm/15/lldb/resource-dir.patch
diff --git a/pkgs/development/compilers/llvm/14/llvm/gnu-install-dirs-polly.patch b/pkgs/development/compilers/llvm/15/llvm/gnu-install-dirs-polly.patch
similarity index 100%
rename from pkgs/development/compilers/llvm/14/llvm/gnu-install-dirs-polly.patch
rename to pkgs/development/compilers/llvm/15/llvm/gnu-install-dirs-polly.patch
diff --git a/pkgs/development/compilers/llvm/14/llvm/no-pipes.patch b/pkgs/development/compilers/llvm/15/llvm/no-pipes.patch
similarity index 100%
rename from pkgs/development/compilers/llvm/14/llvm/no-pipes.patch
rename to pkgs/development/compilers/llvm/15/llvm/no-pipes.patch
diff --git a/pkgs/development/compilers/llvm/14/openmp/run-lit-directly.patch b/pkgs/development/compilers/llvm/15/openmp/run-lit-directly.patch
similarity index 100%
rename from pkgs/development/compilers/llvm/14/openmp/run-lit-directly.patch
rename to pkgs/development/compilers/llvm/15/openmp/run-lit-directly.patch
diff --git a/pkgs/development/compilers/llvm/common/clang/default.nix b/pkgs/development/compilers/llvm/common/clang/default.nix
index 2fa14c5101d0..bfbabb48d480 100644
--- a/pkgs/development/compilers/llvm/common/clang/default.nix
+++ b/pkgs/development/compilers/llvm/common/clang/default.nix
@@ -82,19 +82,13 @@ stdenv.mkDerivation (
     })
     # Backport `__ENVIRONMENT_OS_VERSION_MIN_REQUIRED__` support from Clang 17.
     # This is needed by newer SDKs (14+).
-    ++
-      lib.optional
-        (
-          lib.versionAtLeast (lib.versions.major release_version) "15"
-          && lib.versionOlder (lib.versions.major release_version) "17"
-        )
-        (fetchpatch {
-          name = "clang-darwin-An-OS-version-preprocessor-define.patch";
-          url = "https://github.com/llvm/llvm-project/commit/c8e2dd8c6f490b68e41fe663b44535a8a21dfeab.patch?full_index=1";
-          includes = [ "lib/Basic/Targets/OSTargets.cpp" ];
-          stripLen = 1;
-          hash = "sha256-Vs32kql7N6qtLqc12FtZHURcbenA7+N3E/nRRX3jdig=";
-        })
+    ++ lib.optional (lib.versionOlder (lib.versions.major release_version) "17") (fetchpatch {
+      name = "clang-darwin-An-OS-version-preprocessor-define.patch";
+      url = "https://github.com/llvm/llvm-project/commit/c8e2dd8c6f490b68e41fe663b44535a8a21dfeab.patch?full_index=1";
+      includes = [ "lib/Basic/Targets/OSTargets.cpp" ];
+      stripLen = 1;
+      hash = "sha256-Vs32kql7N6qtLqc12FtZHURcbenA7+N3E/nRRX3jdig=";
+    })
     # Fixes a bunch of lambda-related crashes
     # https://github.com/llvm/llvm-project/pull/93206
     ++ lib.optional (lib.versions.major release_version == "18") (fetchpatch {
@@ -117,8 +111,8 @@ stdenv.mkDerivation (
     nativeBuildInputs = [
       cmake
       python3
+      ninja
     ]
-    ++ (lib.optional (lib.versionAtLeast release_version "15") ninja)
     ++ lib.optional (lib.versionAtLeast version "18" && enableManpages) python3.pkgs.myst-parser
     ++ lib.optional enableManpages python3.pkgs.sphinx
     ++ lib.optional stdenv.hostPlatform.isDarwin fixDarwinDylibNames;
@@ -128,43 +122,41 @@ stdenv.mkDerivation (
       libllvm
     ];
 
-    cmakeFlags =
-      (lib.optionals (lib.versionAtLeast release_version "15") [
-        (lib.cmakeFeature "CLANG_INSTALL_PACKAGE_DIR" "${placeholder "dev"}/lib/cmake/clang")
-      ])
-      ++ [
-        (lib.cmakeBool "CLANGD_BUILD_XPC" false)
-        (lib.cmakeBool "LLVM_ENABLE_RTTI" true)
-        (lib.cmakeFeature "LLVM_TABLEGEN_EXE" "${buildLlvmTools.tblgen}/bin/llvm-tblgen")
-        (lib.cmakeFeature "CLANG_TABLEGEN" "${buildLlvmTools.tblgen}/bin/clang-tblgen")
-      ]
-      ++ lib.optionals (lib.versionAtLeast release_version "21") [
-        (lib.cmakeFeature "CLANG_RESOURCE_DIR" "${placeholder "lib"}/lib/clang/${lib.versions.major release_version}")
-      ]
-      ++ lib.optionals (lib.versionAtLeast release_version "17") [
-        (lib.cmakeBool "LLVM_INCLUDE_TESTS" false)
-      ]
-      ++ lib.optionals enableManpages [
-        (lib.cmakeBool "CLANG_INCLUDE_DOCS" true)
-        (lib.cmakeBool "LLVM_ENABLE_SPHINX" true)
-        (lib.cmakeBool "SPHINX_OUTPUT_MAN" true)
-        (lib.cmakeBool "SPHINX_OUTPUT_HTML" false)
-        (lib.cmakeBool "SPHINX_WARNINGS_AS_ERRORS" false)
-      ]
-      ++ lib.optionals (lib.versionAtLeast release_version "15") [
-        # Added in LLVM15:
-        # `clang-tidy-confusable-chars-gen`: https://github.com/llvm/llvm-project/commit/c3574ef739fbfcc59d405985a3a4fa6f4619ecdb
-        # `clang-pseudo-gen`: https://github.com/llvm/llvm-project/commit/cd2292ef824591cc34cc299910a3098545c840c7
-        (lib.cmakeFeature "CLANG_TIDY_CONFUSABLE_CHARS_GEN" "${buildLlvmTools.tblgen}/bin/clang-tidy-confusable-chars-gen")
-      ]
-      ++ lib.optionals (lib.versionOlder release_version "20") [
-        # clang-pseudo removed in LLVM20: https://github.com/llvm/llvm-project/commit/ed8f78827895050442f544edef2933a60d4a7935
-        (lib.cmakeFeature "CLANG_PSEUDO_GEN" "${buildLlvmTools.tblgen}/bin/clang-pseudo-gen")
-      ]
-      ++ lib.optional (lib.versionAtLeast release_version "20") (
-        lib.cmakeFeature "LLVM_DIR" "${libllvm.dev}/lib/cmake/llvm"
-      )
-      ++ devExtraCmakeFlags;
+    cmakeFlags = [
+      (lib.cmakeFeature "CLANG_INSTALL_PACKAGE_DIR" "${placeholder "dev"}/lib/cmake/clang")
+      (lib.cmakeBool "CLANGD_BUILD_XPC" false)
+      (lib.cmakeBool "LLVM_ENABLE_RTTI" true)
+      (lib.cmakeFeature "LLVM_TABLEGEN_EXE" "${buildLlvmTools.tblgen}/bin/llvm-tblgen")
+      (lib.cmakeFeature "CLANG_TABLEGEN" "${buildLlvmTools.tblgen}/bin/clang-tblgen")
+    ]
+    ++ lib.optionals (lib.versionAtLeast release_version "21") [
+      (lib.cmakeFeature "CLANG_RESOURCE_DIR" "${placeholder "lib"}/lib/clang/${lib.versions.major release_version}")
+    ]
+    ++ lib.optionals (lib.versionAtLeast release_version "17") [
+      (lib.cmakeBool "LLVM_INCLUDE_TESTS" false)
+    ]
+    ++ lib.optionals enableManpages [
+      (lib.cmakeBool "CLANG_INCLUDE_DOCS" true)
+      (lib.cmakeBool "LLVM_ENABLE_SPHINX" true)
+      (lib.cmakeBool "SPHINX_OUTPUT_MAN" true)
+      (lib.cmakeBool "SPHINX_OUTPUT_HTML" false)
+      (lib.cmakeBool "SPHINX_WARNINGS_AS_ERRORS" false)
+    ]
+    # TODO: Clean up on `staging`.
+    ++ [
+      # Added in LLVM15:
+      # `clang-tidy-confusable-chars-gen`: https://github.com/llvm/llvm-project/commit/c3574ef739fbfcc59d405985a3a4fa6f4619ecdb
+      # `clang-pseudo-gen`: https://github.com/llvm/llvm-project/commit/cd2292ef824591cc34cc299910a3098545c840c7
+      (lib.cmakeFeature "CLANG_TIDY_CONFUSABLE_CHARS_GEN" "${buildLlvmTools.tblgen}/bin/clang-tidy-confusable-chars-gen")
+    ]
+    ++ lib.optionals (lib.versionOlder release_version "20") [
+      # clang-pseudo removed in LLVM20: https://github.com/llvm/llvm-project/commit/ed8f78827895050442f544edef2933a60d4a7935
+      (lib.cmakeFeature "CLANG_PSEUDO_GEN" "${buildLlvmTools.tblgen}/bin/clang-pseudo-gen")
+    ]
+    ++ lib.optional (lib.versionAtLeast release_version "20") (
+      lib.cmakeFeature "LLVM_DIR" "${libllvm.dev}/lib/cmake/llvm"
+    )
+    ++ devExtraCmakeFlags;
 
     postPatch = ''
       # Make sure clang passes the correct location of libLTO to ld64
@@ -203,39 +195,21 @@ stdenv.mkDerivation (
       # Move libclang to 'lib' output
       moveToOutput "lib/libclang.*" "$lib"
       moveToOutput "lib/libclang-cpp.*" "$lib"
+      mkdir -p $python/bin $python/share/clang/
     ''
-    + (
-      if lib.versionOlder release_version "15" then
-        ''
-          mkdir -p $python/bin $python/share/{clang,scan-view}
-        ''
-      else
-        ''
-          mkdir -p $python/bin $python/share/clang/
-        ''
-    )
     + ''
       mv $out/bin/{git-clang-format,scan-view} $python/bin
       if [ -e $out/bin/set-xcode-analyzer ]; then
         mv $out/bin/set-xcode-analyzer $python/bin
       fi
       mv $out/share/clang/*.py $python/share/clang
-    ''
-    + (lib.optionalString (lib.versionOlder release_version "15") ''
-      mv $out/share/scan-view/*.py $python/share/scan-view
-    '')
-    + ''
       rm $out/bin/c-index-test
       patchShebangs $python/bin
 
       mkdir -p $dev/bin
     ''
     + (
-      if lib.versionOlder release_version "15" then
-        ''
-          cp bin/clang-tblgen $dev/bin
-        ''
-      else if lib.versionOlder release_version "20" then
+      if lib.versionOlder release_version "20" then
         ''
           cp bin/{clang-tblgen,clang-tidy-confusable-chars-gen,clang-pseudo-gen} $dev/bin
         ''
@@ -246,12 +220,7 @@ stdenv.mkDerivation (
     );
 
     env =
-      lib.optionalAttrs
-        (
-          stdenv.buildPlatform != stdenv.hostPlatform
-          && !stdenv.hostPlatform.useLLVM
-          && lib.versionAtLeast release_version "15"
-        )
+      lib.optionalAttrs (stdenv.buildPlatform != stdenv.hostPlatform && !stdenv.hostPlatform.useLLVM)
         {
           # The following warning is triggered with (at least) gcc >=
           # 12, but appears to occur only for cross compiles.
@@ -268,7 +237,6 @@ stdenv.mkDerivation (
         ++ lib.optional (!targetPlatform.isAarch64 || !targetPlatform.isLinux) "pacret"
         ++ lib.optional (
           (targetPlatform.isAarch64 && (lib.versionOlder release_version "18.1"))
-          || (targetPlatform.isFreeBSD && (lib.versionOlder release_version "15"))
           || !(targetPlatform.isLinux || targetPlatform.isFreeBSD)
           || !(
             targetPlatform.isx86
@@ -277,10 +245,7 @@ stdenv.mkDerivation (
             || targetPlatform.isAarch64
           )
         ) "stackclashprotection"
-        ++ lib.optional (
-          (lib.versionOlder release_version "15") || !(targetPlatform.isx86_64 || targetPlatform.isAarch64)
-        ) "zerocallusedregs"
-        ++ lib.optional (lib.versionOlder release_version "15") "strictflexarrays1"
+        ++ lib.optional (!(targetPlatform.isx86_64 || targetPlatform.isAarch64)) "zerocallusedregs"
         ++ lib.optional (lib.versionOlder release_version "16") "strictflexarrays3"
         ++ (finalAttrs.passthru.hardeningUnsupportedFlags or [ ]);
     };
@@ -303,35 +268,23 @@ stdenv.mkDerivation (
       mainProgram = "clang";
     };
   }
-  // lib.optionalAttrs enableManpages (
-    {
-      pname = "clang-manpages";
+  // lib.optionalAttrs enableManpages {
+    pname = "clang-manpages";
 
-      installPhase = ''
-        mkdir -p $out/share/man/man1
-        # Manually install clang manpage
-        cp docs/man/*.1 $out/share/man/man1/
-      '';
+    ninjaFlags = [ "docs-clang-man" ];
 
-      outputs = [ "out" ];
+    installPhase = ''
+      mkdir -p $out/share/man/man1
+      # Manually install clang manpage
+      cp docs/man/*.1 $out/share/man/man1/
+    '';
 
-      doCheck = false;
+    outputs = [ "out" ];
 
-      meta = llvm_meta // {
-        description = "man page for Clang ${version}";
-      };
-    }
-    // (
-      if lib.versionOlder release_version "15" then
-        {
-          buildPhase = ''
-            make docs-clang-man
-          '';
-        }
-      else
-        {
-          ninjaFlags = [ "docs-clang-man" ];
-        }
-    )
-  )
+    doCheck = false;
+
+    meta = llvm_meta // {
+      description = "man page for Clang ${version}";
+    };
+  }
 )
diff --git a/pkgs/development/compilers/llvm/common/compiler-rt/armv6-mcr-dmb.patch b/pkgs/development/compilers/llvm/common/compiler-rt/armv6-mcr-dmb.patch
deleted file mode 100644
index acdcc9e983b8..000000000000
--- a/pkgs/development/compilers/llvm/common/compiler-rt/armv6-mcr-dmb.patch
+++ /dev/null
@@ -1,75 +0,0 @@
-From a11d1cc41c725ec6dee58f75e4a852a658dd7543 Mon Sep 17 00:00:00 2001
-From: Khem Raj <raj.khem@gmail.com>
-Date: Thu, 10 Mar 2022 19:30:00 -0800
-Subject: [PATCH] [builtins] Use mcr for dmb instruction on armv6
-
-At present compiler-rt cross compiles for armv6 ( -march=armv6 ) but includes
-dmb instructions which are only available in armv7+ this causes SIGILL on
-clang+compiler-rt compiled components on rpi0w platforms.
-
-Reviewed By: MaskRay
-
-Differential Revision: https://reviews.llvm.org/D99282
----
- compiler-rt/lib/builtins/arm/sync-ops.h | 8 ++++----
- compiler-rt/lib/builtins/assembly.h     | 8 ++++++++
- 2 files changed, 12 insertions(+), 4 deletions(-)
-
-diff --git a/lib/builtins/arm/sync-ops.h b/lib/builtins/arm/sync-ops.h
-index c9623249e5d20..7a26170741ad2 100644
---- a/lib/builtins/arm/sync-ops.h
-+++ b/lib/builtins/arm/sync-ops.h
-@@ -19,14 +19,14 @@
-   .thumb;                                                                      \
-   .syntax unified;                                                             \
-   DEFINE_COMPILERRT_THUMB_FUNCTION(__sync_fetch_and_##op)                      \
--  dmb;                                                                         \
-+  DMB;                                                                         \
-   mov r12, r0;                                                                 \
-   LOCAL_LABEL(tryatomic_##op) : ldrex r0, [r12];                               \
-   op(r2, r0, r1);                                                              \
-   strex r3, r2, [r12];                                                         \
-   cmp r3, #0;                                                                  \
-   bne LOCAL_LABEL(tryatomic_##op);                                             \
--  dmb;                                                                         \
-+  DMB;                                                                         \
-   bx lr
- 
- #define SYNC_OP_8(op)                                                          \
-@@ -35,14 +35,14 @@
-   .syntax unified;                                                             \
-   DEFINE_COMPILERRT_THUMB_FUNCTION(__sync_fetch_and_##op)                      \
-   push {r4, r5, r6, lr};                                                       \
--  dmb;                                                                         \
-+  DMB;                                                                         \
-   mov r12, r0;                                                                 \
-   LOCAL_LABEL(tryatomic_##op) : ldrexd r0, r1, [r12];                          \
-   op(r4, r5, r0, r1, r2, r3);                                                  \
-   strexd r6, r4, r5, [r12];                                                    \
-   cmp r6, #0;                                                                  \
-   bne LOCAL_LABEL(tryatomic_##op);                                             \
--  dmb;                                                                         \
-+  DMB;                                                                         \
-   pop { r4, r5, r6, pc }
- 
- #define MINMAX_4(rD, rN, rM, cmp_kind)                                         \
-diff --git a/lib/builtins/assembly.h b/lib/builtins/assembly.h
-index 69a3d8620f924..06aa18162e3b4 100644
---- a/lib/builtins/assembly.h
-+++ b/lib/builtins/assembly.h
-@@ -189,6 +189,14 @@
-   JMP(ip)
- #endif
- 
-+#if __ARM_ARCH >= 7
-+#define DMB dmb
-+#elif __ARM_ARCH >= 6
-+#define DMB mcr p15, #0, r0, c7, c10, #5
-+#else
-+#error only supported on ARMv6+
-+#endif
-+
- #if defined(USE_THUMB_2)
- #define WIDE(op) op.w
- #else
-
diff --git a/pkgs/development/compilers/llvm/common/compiler-rt/armv6-sync-ops-no-thumb.patch b/pkgs/development/compilers/llvm/common/compiler-rt/armv6-sync-ops-no-thumb.patch
deleted file mode 100644
index 098a155d448c..000000000000
--- a/pkgs/development/compilers/llvm/common/compiler-rt/armv6-sync-ops-no-thumb.patch
+++ /dev/null
@@ -1,52 +0,0 @@
-From 5017de8ba4b1fe985169cf54590e858a9019a91f Mon Sep 17 00:00:00 2001
-From: Khem Raj <raj.khem@gmail.com>
-Date: Fri, 11 Mar 2022 16:25:49 -0800
-Subject: [PATCH] [builtins] Do not force thumb mode directive in
- arm/sync-ops.h
-
-.thumb_func was not switching mode until [1]
-so it did not show up but now that .thumb_func (without argument) is
-switching mode, its causing build failures on armv6 ( rpi0 ) even when
-build is explicitly asking for this file to be built with -marm (ARM
-mode), therefore use DEFINE_COMPILERRT_FUNCTION macro to add function
-header which considers arch and mode from compiler cmdline to decide if
-the function is built using thumb mode or arm mode.
-
-[1] https://reviews.llvm.org/D101975
-
-Note that it also needs https://reviews.llvm.org/D99282
-
-Reviewed By: peter.smith, MaskRay
-
-Differential Revision: https://reviews.llvm.org/D104183
----
- compiler-rt/lib/builtins/arm/sync-ops.h | 6 ++----
- 1 file changed, 2 insertions(+), 4 deletions(-)
-
-diff --git a/lib/builtins/arm/sync-ops.h b/lib/builtins/arm/sync-ops.h
-index 7a26170741ad2..d914f9d3a1093 100644
---- a/lib/builtins/arm/sync-ops.h
-+++ b/lib/builtins/arm/sync-ops.h
-@@ -16,9 +16,8 @@
- 
- #define SYNC_OP_4(op)                                                          \
-   .p2align 2;                                                                  \
--  .thumb;                                                                      \
-   .syntax unified;                                                             \
--  DEFINE_COMPILERRT_THUMB_FUNCTION(__sync_fetch_and_##op)                      \
-+  DEFINE_COMPILERRT_FUNCTION(__sync_fetch_and_##op)                            \
-   DMB;                                                                         \
-   mov r12, r0;                                                                 \
-   LOCAL_LABEL(tryatomic_##op) : ldrex r0, [r12];                               \
-@@ -31,9 +30,8 @@
- 
- #define SYNC_OP_8(op)                                                          \
-   .p2align 2;                                                                  \
--  .thumb;                                                                      \
-   .syntax unified;                                                             \
--  DEFINE_COMPILERRT_THUMB_FUNCTION(__sync_fetch_and_##op)                      \
-+  DEFINE_COMPILERRT_FUNCTION(__sync_fetch_and_##op)                            \
-   push {r4, r5, r6, lr};                                                       \
-   DMB;                                                                         \
-   mov r12, r0;                                                                 \
-
diff --git a/pkgs/development/compilers/llvm/common/compiler-rt/default.nix b/pkgs/development/compilers/llvm/common/compiler-rt/default.nix
index 6a9011db7cf2..31def30e04ca 100644
--- a/pkgs/development/compilers/llvm/common/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/common/compiler-rt/default.nix
@@ -72,64 +72,54 @@ stdenv.mkDerivation (finalAttrs: {
 
   sourceRoot = "${finalAttrs.src.name}/compiler-rt";
 
-  patches =
-    lib.optional (lib.versionOlder release_version "15") (getVersionFile "compiler-rt/codesign.patch") # Revert compiler-rt commit that makes codesign mandatory
-    ++ [
-      (getVersionFile "compiler-rt/X86-support-extension.patch") # Add support for i486 i586 i686 by reusing i386 config
-      # ld-wrapper dislikes `-rpath-link //nix/store`, so we normalize away the
-      # extra `/`.
-      (getVersionFile "compiler-rt/normalize-var.patch")
-      # Fix build on armv6l
-      ./armv6-no-ldrexd-strexd.patch
-    ]
-    ++ lib.optional (lib.versionOlder release_version "18") (
-      getVersionFile "compiler-rt/gnu-install-dirs.patch"
-    )
-    ++ lib.optional (lib.versionOlder release_version "18") (fetchpatch {
-      name = "cfi_startproc-after-label.patch";
-      url = "https://github.com/llvm/llvm-project/commit/7939ce39dac0078fef7183d6198598b99c652c88.patch";
-      stripLen = 1;
-      hash = "sha256-tGqXsYvUllFrPa/r/dsKVlwx5IrcJGccuR1WAtUg7/o=";
-    })
-    ++
-      lib.optional (lib.versionOlder release_version "18")
-        # Prevent a compilation error on darwin
-        (getVersionFile "compiler-rt/darwin-targetconditionals.patch")
-    # TODO: make unconditional and remove in <15 section below. Causes rebuilds.
-    ++ lib.optionals (lib.versionAtLeast release_version "15") [
-      # See: https://github.com/NixOS/nixpkgs/pull/186575
-      ./darwin-plistbuddy-workaround.patch
-    ]
-    ++
-      lib.optional (lib.versions.major release_version == "15")
-        # See: https://github.com/NixOS/nixpkgs/pull/194634#discussion_r999829893
-        ./armv7l-15.patch
-    ++ lib.optionals (lib.versionOlder release_version "15") [
-      ./darwin-plistbuddy-workaround.patch
-      (getVersionFile "compiler-rt/armv7l.patch")
-      # Fix build on armv6l
-      ./armv6-mcr-dmb.patch
-      ./armv6-sync-ops-no-thumb.patch
-    ]
-    ++ lib.optionals (lib.versionOlder release_version "18") [
-      # Fix build on armv6l
-      ./armv6-scudo-no-yield.patch
-    ]
-    ++ [
-      (getVersionFile "compiler-rt/armv6-scudo-libatomic.patch")
-    ]
-    ++ lib.optional (lib.versions.major release_version == "19") (fetchpatch {
-      url = "https://github.com/llvm/llvm-project/pull/99837/commits/14ae0a660a38e1feb151928a14f35ff0f4487351.patch";
-      hash = "sha256-JykABCaNNhYhZQxCvKiBn54DZ5ZguksgCHnpdwWF2no=";
-      relative = "compiler-rt";
-    });
+  patches = [
+    (getVersionFile "compiler-rt/X86-support-extension.patch") # Add support for i486 i586 i686 by reusing i386 config
+    # ld-wrapper dislikes `-rpath-link //nix/store`, so we normalize away the
+    # extra `/`.
+    (getVersionFile "compiler-rt/normalize-var.patch")
+    # Fix build on armv6l
+    ./armv6-no-ldrexd-strexd.patch
+  ]
+  ++ lib.optional (lib.versionOlder release_version "18") (
+    getVersionFile "compiler-rt/gnu-install-dirs.patch"
+  )
+  ++ lib.optional (lib.versionOlder release_version "18") (fetchpatch {
+    name = "cfi_startproc-after-label.patch";
+    url = "https://github.com/llvm/llvm-project/commit/7939ce39dac0078fef7183d6198598b99c652c88.patch";
+    stripLen = 1;
+    hash = "sha256-tGqXsYvUllFrPa/r/dsKVlwx5IrcJGccuR1WAtUg7/o=";
+  })
+  ++
+    lib.optional (lib.versionOlder release_version "18")
+      # Prevent a compilation error on darwin
+      (getVersionFile "compiler-rt/darwin-targetconditionals.patch")
+  ++ [
+    # See: https://github.com/NixOS/nixpkgs/pull/186575
+    ./darwin-plistbuddy-workaround.patch
+  ]
+  ++
+    lib.optional (lib.versions.major release_version == "15")
+      # See: https://github.com/NixOS/nixpkgs/pull/194634#discussion_r999829893
+      ./armv7l-15.patch
+  ++ lib.optionals (lib.versionOlder release_version "18") [
+    # Fix build on armv6l
+    ./armv6-scudo-no-yield.patch
+  ]
+  ++ [
+    (getVersionFile "compiler-rt/armv6-scudo-libatomic.patch")
+  ]
+  ++ lib.optional (lib.versions.major release_version == "19") (fetchpatch {
+    url = "https://github.com/llvm/llvm-project/pull/99837/commits/14ae0a660a38e1feb151928a14f35ff0f4487351.patch";
+    hash = "sha256-JykABCaNNhYhZQxCvKiBn54DZ5ZguksgCHnpdwWF2no=";
+    relative = "compiler-rt";
+  });
 
   nativeBuildInputs = [
     cmake
     python3
     libllvm.dev
+    ninja
   ]
-  ++ (lib.optional (lib.versionAtLeast release_version "15") ninja)
   ++ lib.optionals stdenv.hostPlatform.isDarwin [ jq ];
   buildInputs =
     lib.optional (stdenv.hostPlatform.isLinux && stdenv.hostPlatform.isRiscV) linuxHeaders
@@ -214,8 +204,6 @@ stdenv.mkDerivation (finalAttrs: {
       (lib.cmakeFeature "DARWIN_osx_ARCHS" stdenv.hostPlatform.darwinArch)
       (lib.cmakeFeature "DARWIN_osx_BUILTIN_ARCHS" stdenv.hostPlatform.darwinArch)
       (lib.cmakeFeature "SANITIZER_MIN_OSX_VERSION" stdenv.hostPlatform.darwinMinVersion)
-    ]
-    ++ lib.optionals (lib.versionAtLeast release_version "15") [
       # `COMPILER_RT_DEFAULT_TARGET_ONLY` does not apply to Darwin:
       # https://github.com/llvm/llvm-project/blob/27ef42bec80b6c010b7b3729ed0528619521a690/compiler-rt/cmake/base-config-ix.cmake#L153
       (lib.cmakeBool "COMPILER_RT_ENABLE_IOS" false)
diff --git a/pkgs/development/compilers/llvm/common/default.nix b/pkgs/development/compilers/llvm/common/default.nix
index 757ea9feb7a5..c431acde0c7b 100644
--- a/pkgs/development/compilers/llvm/common/default.nix
+++ b/pkgs/development/compilers/llvm/common/default.nix
@@ -257,6 +257,13 @@ let
         }
       );
 
+      lldb-manpages = lowPrio (
+        tools.lldb.override {
+          enableManpages = true;
+          python3 = pkgs.python3; # don't use python-boot
+        }
+      );
+
       # Below, is the LLVM bootstrapping logic. It handles building a
       # fully LLVM toolchain from scratch. No GCC toolchain should be
       # pulled in. As a consequence, it is very quick to build different
@@ -349,9 +356,7 @@ let
           "-B${targetLlvmLibraries.compiler-rt-no-libc}/lib"
           "-nostdlib++"
         ]
-        ++ lib.optional (
-          lib.versionAtLeast metadata.release_version "15" && stdenv.targetPlatform.isWasm
-        ) "-fno-exceptions";
+        ++ lib.optional stdenv.targetPlatform.isWasm "-fno-exceptions";
       };
 
       clangNoLibcWithBasicRt = wrapCCWith rec {
@@ -364,9 +369,7 @@ let
           "-rtlib=compiler-rt"
           "-B${targetLlvmLibraries.compiler-rt-no-libc}/lib"
         ]
-        ++ lib.optional (
-          lib.versionAtLeast metadata.release_version "15" && stdenv.targetPlatform.isWasm
-        ) "-fno-exceptions";
+        ++ lib.optional stdenv.targetPlatform.isWasm "-fno-exceptions";
       };
 
       clangNoLibcNoRt = wrapCCWith rec {
@@ -376,9 +379,7 @@ let
         extraPackages = [ ];
         # "-nostartfiles" used to be needed for pkgsLLVM, causes problems so don't include it.
         extraBuildCommands = mkExtraBuildCommands0 cc;
-        nixSupport.cc-cflags = lib.optional (
-          lib.versionAtLeast metadata.release_version "15" && stdenv.targetPlatform.isWasm
-        ) "-fno-exceptions";
+        nixSupport.cc-cflags = lib.optional stdenv.targetPlatform.isWasm "-fno-exceptions";
       };
 
       # This is an "oddly ordered" bootstrap just for Darwin. Probably
@@ -392,24 +393,15 @@ let
           extraBuildCommands = mkExtraBuildCommands0 cc;
         }
         # FIXME: This should be inside the `wrapCCWith` call.
-        // lib.optionalAttrs (
-          lib.versionAtLeast metadata.release_version "15" && stdenv.targetPlatform.isWasm
-        ) { nixSupport.cc-cflags = [ "-fno-exceptions" ]; };
+        // lib.optionalAttrs stdenv.targetPlatform.isWasm {
+          nixSupport.cc-cflags = [ "-fno-exceptions" ];
+        };
 
       # Aliases
       clangNoCompilerRt = tools.clangNoLibcNoRt;
       clangNoLibc = tools.clangNoLibcWithBasicRt;
       clangNoLibcxx = tools.clangWithLibcAndBasicRt;
     }
-    // lib.optionalAttrs (lib.versionAtLeast metadata.release_version "15") {
-      # TODO: pre-15: lldb/docs/index.rst:155:toctree contains reference to nonexisting document 'design/structureddataplugins'
-      lldb-manpages = lowPrio (
-        tools.lldb.override {
-          enableManpages = true;
-          python3 = pkgs.python3; # don't use python-boot
-        }
-      );
-    }
     // lib.optionalAttrs (lib.versionAtLeast metadata.release_version "16") {
       mlir = callPackage ./mlir { };
     }
diff --git a/pkgs/development/compilers/llvm/common/libc/default.nix b/pkgs/development/compilers/llvm/common/libc/default.nix
index 1942671a782b..d5f6b0b55e39 100644
--- a/pkgs/development/compilers/llvm/common/libc/default.nix
+++ b/pkgs/development/compilers/llvm/common/libc/default.nix
@@ -42,8 +42,8 @@ stdenv.mkDerivation (finalAttrs: {
   nativeBuildInputs = [
     cmake
     python3
+    ninja
   ]
-  ++ (lib.optional (lib.versionAtLeast release_version "15") ninja)
   ++ (lib.optional isFullBuild python3Packages.pyyaml);
 
   buildInputs = lib.optional isFullBuild linuxHeaders;
diff --git a/pkgs/development/compilers/llvm/common/libcxx/default.nix b/pkgs/development/compilers/llvm/common/libcxx/default.nix
index 96d879bfce37..3a5b777c0d64 100644
--- a/pkgs/development/compilers/llvm/common/libcxx/default.nix
+++ b/pkgs/development/compilers/llvm/common/libcxx/default.nix
@@ -266,16 +266,9 @@ stdenv.mkDerivation (
   // (
     if (lib.versionOlder release_version "16" || lib.versionAtLeast release_version "17") then
       {
-        postPatch =
-          (lib.optionalString (lib.versionOlder release_version "15") ''
-            # fix CMake error when static and LIBCXXABI_USE_LLVM_UNWINDER=ON. aren't
-            # building unwind so don't need to depend on it
-            substituteInPlace libcxx/src/CMakeLists.txt \
-              --replace-fail "add_dependencies(cxx_static unwind)" "# add_dependencies(cxx_static unwind)"
-          '')
-          + ''
-            cd runtimes
-          '';
+        postPatch = ''
+          cd runtimes
+        '';
       }
     else
       {
diff --git a/pkgs/development/compilers/llvm/common/libunwind/default.nix b/pkgs/development/compilers/llvm/common/libunwind/default.nix
index 180090fbfede..6d4d9bb60e5c 100644
--- a/pkgs/development/compilers/llvm/common/libunwind/default.nix
+++ b/pkgs/development/compilers/llvm/common/libunwind/default.nix
@@ -32,30 +32,22 @@ stdenv.mkDerivation (
 
     src =
       if monorepoSrc != null then
-        runCommand "libunwind-src-${version}" { inherit (monorepoSrc) passthru; } (
-          ''
-            mkdir -p "$out"
-            cp -r ${monorepoSrc}/cmake "$out"
-            cp -r ${monorepoSrc}/libunwind "$out"
-            mkdir -p "$out/libcxx"
-            cp -r ${monorepoSrc}/libcxx/cmake "$out/libcxx"
-            cp -r ${monorepoSrc}/libcxx/utils "$out/libcxx"
-            mkdir -p "$out/llvm"
-            cp -r ${monorepoSrc}/llvm/cmake "$out/llvm"
-          ''
-          + lib.optionalString (lib.versionAtLeast release_version "15") ''
-            cp -r ${monorepoSrc}/llvm/utils "$out/llvm"
-            cp -r ${monorepoSrc}/runtimes "$out"
-          ''
-        )
+        runCommand "libunwind-src-${version}" { inherit (monorepoSrc) passthru; } ''
+          mkdir -p "$out"
+          cp -r ${monorepoSrc}/cmake "$out"
+          cp -r ${monorepoSrc}/libunwind "$out"
+          mkdir -p "$out/libcxx"
+          cp -r ${monorepoSrc}/libcxx/cmake "$out/libcxx"
+          cp -r ${monorepoSrc}/libcxx/utils "$out/libcxx"
+          mkdir -p "$out/llvm"
+          cp -r ${monorepoSrc}/llvm/cmake "$out/llvm"
+          cp -r ${monorepoSrc}/llvm/utils "$out/llvm"
+          cp -r ${monorepoSrc}/runtimes "$out"
+        ''
       else
         src;
 
-    sourceRoot =
-      if lib.versionAtLeast release_version "15" then
-        "${finalAttrs.src.name}/runtimes"
-      else
-        "${finalAttrs.src.name}/libunwind";
+    sourceRoot = "${finalAttrs.src.name}/runtimes";
 
     outputs = [
       "out"
@@ -64,34 +56,24 @@ stdenv.mkDerivation (
 
     nativeBuildInputs = [
       cmake
-    ]
-    ++ lib.optionals (lib.versionAtLeast release_version "15") [
       ninja
       python3
     ];
 
     cmakeFlags = [
       (lib.cmakeBool "LIBUNWIND_ENABLE_SHARED" enableShared)
+      (lib.cmakeFeature "LLVM_ENABLE_RUNTIMES" "libunwind")
     ]
-    ++ lib.optional (lib.versionAtLeast release_version "15") (
-      lib.cmakeFeature "LLVM_ENABLE_RUNTIMES" "libunwind"
-    )
     ++ devExtraCmakeFlags;
 
-    prePatch =
-      lib.optionalString
-        (lib.versionAtLeast release_version "15" && (hasPatches || lib.versionOlder release_version "18"))
-        ''
-          cd ../libunwind
-          chmod -R u+w .
-        '';
+    prePatch = lib.optionalString (hasPatches || lib.versionOlder release_version "18") ''
+      cd ../libunwind
+      chmod -R u+w .
+    '';
 
-    postPatch =
-      lib.optionalString
-        (lib.versionAtLeast release_version "15" && (hasPatches || lib.versionOlder release_version "18"))
-        ''
-          cd ../runtimes
-        '';
+    postPatch = lib.optionalString (hasPatches || lib.versionOlder release_version "18") ''
+      cd ../runtimes
+    '';
 
     postInstall =
       lib.optionalString (enableShared && !stdenv.hostPlatform.isDarwin && !stdenv.hostPlatform.isWindows)
diff --git a/pkgs/development/compilers/llvm/common/lld/default.nix b/pkgs/development/compilers/llvm/common/lld/default.nix
index 32a938fdc21b..da9a59944761 100644
--- a/pkgs/development/compilers/llvm/common/lld/default.nix
+++ b/pkgs/development/compilers/llvm/common/lld/default.nix
@@ -38,9 +38,6 @@ stdenv.mkDerivation (finalAttrs: {
   patches = [
     (getVersionFile "lld/gnu-install-dirs.patch")
   ]
-  ++ lib.optional (lib.versions.major release_version == "14") (
-    getVersionFile "lld/fix-root-src-dir.patch"
-  )
   ++ lib.optional (lib.versionAtLeast release_version "16" && lib.versionOlder release_version "18") (
     getVersionFile "lld/add-table-base.patch"
   )
@@ -54,20 +51,20 @@ stdenv.mkDerivation (finalAttrs: {
     }
   );
 
-  nativeBuildInputs = [ cmake ] ++ lib.optional (lib.versionAtLeast release_version "15") ninja;
+  nativeBuildInputs = [
+    cmake
+    ninja
+  ];
   buildInputs = [
     libllvm
     libxml2
   ];
 
-  cmakeFlags =
-    lib.optionals (lib.versionAtLeast release_version "15") [
-      (lib.cmakeFeature "LLD_INSTALL_PACKAGE_DIR" "${placeholder "dev"}/lib/cmake/lld")
-    ]
-    ++ [
-      (lib.cmakeFeature "LLVM_TABLEGEN_EXE" "${buildLlvmTools.tblgen}/bin/llvm-tblgen")
-    ]
-    ++ devExtraCmakeFlags;
+  cmakeFlags = [
+    (lib.cmakeFeature "LLD_INSTALL_PACKAGE_DIR" "${placeholder "dev"}/lib/cmake/lld")
+    (lib.cmakeFeature "LLVM_TABLEGEN_EXE" "${buildLlvmTools.tblgen}/bin/llvm-tblgen")
+  ]
+  ++ devExtraCmakeFlags;
 
   # TODO: Remove on `staging`.
   postPatch = "";
diff --git a/pkgs/development/compilers/llvm/common/lldb/default.nix b/pkgs/development/compilers/llvm/common/lldb/default.nix
index 5e4c5f34ecb8..24404d97de90 100644
--- a/pkgs/development/compilers/llvm/common/lldb/default.nix
+++ b/pkgs/development/compilers/llvm/common/lldb/default.nix
@@ -78,20 +78,7 @@ stdenv.mkDerivation (
           }).overrideAttrs
             (_: _: { name = "resource-dir.patch"; });
       in
-      lib.optionals (lib.versionOlder release_version "15") [
-        # Fixes for SWIG 4
-        (fetchpatch2 {
-          url = "https://github.com/llvm/llvm-project/commit/81fc5f7909a4ef5a8d4b5da2a10f77f7cb01ba63.patch?full_index=1";
-          stripLen = 1;
-          hash = "sha256-Znw+C0uEw7lGETQLKPBZV/Ymo2UigZS+Hv/j1mUo7p0=";
-        })
-        (fetchpatch2 {
-          url = "https://github.com/llvm/llvm-project/commit/f0a25fe0b746f56295d5c02116ba28d2f965c175.patch?full_index=1";
-          stripLen = 1;
-          hash = "sha256-QzVeZzmc99xIMiO7n//b+RNAvmxghISKQD93U2zOgFI=";
-        })
-      ]
-      ++ lib.optionals (lib.versionOlder release_version "16") [
+      lib.optionals (lib.versionOlder release_version "16") [
         # Fixes for SWIG 4
         (fetchpatch2 {
           url = "https://github.com/llvm/llvm-project/commit/ba35c27ec9aa9807f5b4be2a0c33ca9b045accc7.patch?full_index=1";
@@ -181,21 +168,17 @@ stdenv.mkDerivation (
     ++ lib.optionals (lib.versionAtLeast release_version "17") [
       (lib.cmakeFeature "CLANG_RESOURCE_DIR" "../../../../${lib.getLib libclang}")
     ]
-    ++ lib.optionals enableManpages (
-      [
-        (lib.cmakeBool "LLVM_ENABLE_SPHINX" true)
-        (lib.cmakeBool "SPHINX_OUTPUT_MAN" true)
-        (lib.cmakeBool "SPHINX_OUTPUT_HTML" false)
-      ]
-      ++ lib.optionals (lib.versionAtLeast release_version "15") [
-        # docs reference `automodapi` but it's not added to the extensions list when
-        # only building the manpages:
-        # https://github.com/llvm/llvm-project/blob/af6ec9200b09039573d85e349496c4f5b17c3d7f/lldb/docs/conf.py#L54
-        #
-        # so, we just ignore the resulting errors
-        (lib.cmakeBool "SPHINX_WARNINGS_AS_ERRORS" false)
-      ]
-    )
+    ++ lib.optionals enableManpages [
+      (lib.cmakeBool "LLVM_ENABLE_SPHINX" true)
+      (lib.cmakeBool "SPHINX_OUTPUT_MAN" true)
+      (lib.cmakeBool "SPHINX_OUTPUT_HTML" false)
+      # docs reference `automodapi` but it's not added to the extensions list when
+      # only building the manpages:
+      # https://github.com/llvm/llvm-project/blob/af6ec9200b09039573d85e349496c4f5b17c3d7f/lldb/docs/conf.py#L54
+      #
+      # so, we just ignore the resulting errors
+      (lib.cmakeBool "SPHINX_WARNINGS_AS_ERRORS" false)
+    ]
     ++ lib.optionals finalAttrs.finalPackage.doCheck [
       (lib.cmakeFeature "LLDB_TEST_C_COMPILER" "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc")
       (lib.cmakeFeature "-DLLDB_TEST_CXX_COMPILER" "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}c++")
@@ -203,7 +186,7 @@ stdenv.mkDerivation (
     ++ devExtraCmakeFlags;
 
     doCheck = false;
-    doInstallCheck = lib.versionOlder release_version "15";
+    doInstallCheck = false;
 
     # TODO: cleanup with mass-rebuild
     installCheckPhase = ''
@@ -248,11 +231,10 @@ stdenv.mkDerivation (
   // lib.optionalAttrs enableManpages {
     pname = "lldb-manpages";
 
-    buildPhase = lib.optionalString (lib.versionOlder release_version "15") ''
-      make docs-lldb-man
-    '';
+    # TODO: Remove on `staging`.
+    buildPhase = "";
 
-    ninjaFlags = lib.optionals (lib.versionAtLeast release_version "15") [ "docs-lldb-man" ];
+    ninjaFlags = [ "docs-lldb-man" ];
 
     propagatedBuildInputs = [ ];
 
diff --git a/pkgs/development/compilers/llvm/common/llvm/default.nix b/pkgs/development/compilers/llvm/common/llvm/default.nix
index d92398a7e818..903202cdc813 100644
--- a/pkgs/development/compilers/llvm/common/llvm/default.nix
+++ b/pkgs/development/compilers/llvm/common/llvm/default.nix
@@ -125,7 +125,7 @@ stdenv.mkDerivation (
       # Originally based off https://reviews.llvm.org/D99484
       # Latest state: https://github.com/llvm/llvm-project/pull/125376
       [ (getVersionFile "llvm/gnu-install-dirs.patch") ]
-      ++ lib.optionals (lib.versionAtLeast release_version "15") [
+      ++ [
         # Running the tests involves invoking binaries (like `opt`) that depend on
         # the LLVM dylibs and reference them by absolute install path (i.e. their
         # nix store path).
@@ -240,10 +240,10 @@ stdenv.mkDerivation (
         # Just like the `gnu-install-dirs` patch, but for `polly`.
         (getVersionFile "llvm/gnu-install-dirs-polly.patch")
       ]
-      ++
-        lib.optional (lib.versionAtLeast release_version "15")
-          # Just like the `llvm-lit-cfg` patch, but for `polly`.
-          (getVersionFile "llvm/polly-lit-cfg-add-libs-to-dylib-path.patch")
+      ++ [
+        # Just like the `llvm-lit-cfg` patch, but for `polly`.
+        (getVersionFile "llvm/polly-lit-cfg-add-libs-to-dylib-path.patch")
+      ]
       ++
         lib.optional (lib.versions.major release_version == "20")
           # Test failure on riscv64, fixed in llvm 21
@@ -262,8 +262,8 @@ stdenv.mkDerivation (
       # this is needed until scripts are updated to not use /usr/bin/uname on FreeBSD native
       updateAutotoolsGnuConfigScriptsHook
       python
+      ninja
     ]
-    ++ (lib.optional (lib.versionAtLeast release_version "15") ninja)
     ++ optionals enableManpages [
       # Note: we intentionally use `python3Packages` instead of `python3.pkgs`;
       # splicing does *not* work with the latter. (TODO: fix)
@@ -290,7 +290,7 @@ stdenv.mkDerivation (
     nativeCheckInputs = [
       which
     ]
-    ++ lib.optional (stdenv.hostPlatform.isDarwin && lib.versionAtLeast release_version "15") sysctl;
+    ++ lib.optional stdenv.hostPlatform.isDarwin sysctl;
 
     postPatch =
       optionalString stdenv.hostPlatform.isDarwin (
@@ -301,119 +301,113 @@ stdenv.mkDerivation (
         +
           # As of LLVM 15, marked as XFAIL on arm64 macOS but lit doesn't seem to pick
           # this up: https://github.com/llvm/llvm-project/blob/c344d97a125b18f8fed0a64aace73c49a870e079/llvm/test/MC/ELF/cfi-version.ll#L7
-          (optionalString (lib.versionAtLeast release_version "15") (
-            ''
-              rm test/MC/ELF/cfi-version.ll
+          ''
+            rm test/MC/ELF/cfi-version.ll
 
-            ''
-            +
-              # This test tries to call `sw_vers` by absolute path (`/usr/bin/sw_vers`)
-              # and thus fails under the sandbox:
-              (
-                if lib.versionAtLeast release_version "16" then
-                  ''
-                    substituteInPlace unittests/TargetParser/Host.cpp \
-                      --replace-fail '/usr/bin/sw_vers' "${(builtins.toString darwin.DarwinTools) + "/bin/sw_vers"}"
-                  ''
-                else
-                  ''
-                    substituteInPlace unittests/Support/Host.cpp \
-                      --replace-fail '/usr/bin/sw_vers' "${(builtins.toString darwin.DarwinTools) + "/bin/sw_vers"}"
-                  ''
-              )
-            +
-              # This test tries to call the intrinsics `@llvm.roundeven.f32` and
-              # `@llvm.roundeven.f64` which seem to (incorrectly?) lower to `roundevenf`
-              # and `roundeven` on macOS and FreeBSD.
-              #
-              # However these functions are glibc specific so the test fails:
-              #   - https://www.gnu.org/software/gnulib/manual/html_node/roundevenf.html
-              #   - https://www.gnu.org/software/gnulib/manual/html_node/roundeven.html
-              #
-              # TODO(@rrbutani): this seems to run fine on `aarch64-darwin`, why does it
-              # pass there?
-              optionalString (lib.versionAtLeast release_version "16") ''
-                substituteInPlace test/ExecutionEngine/Interpreter/intrinsics.ll \
-                  --replace-fail "%roundeven32 = call float @llvm.roundeven.f32(float 0.000000e+00)" "" \
-                  --replace-fail "%roundeven64 = call double @llvm.roundeven.f64(double 0.000000e+00)" ""
+          ''
+        +
+          # This test tries to call `sw_vers` by absolute path (`/usr/bin/sw_vers`)
+          # and thus fails under the sandbox:
+          (
+            if lib.versionAtLeast release_version "16" then
               ''
-            +
-              # fails when run in sandbox
-              optionalString (!stdenv.hostPlatform.isx86 && lib.versionAtLeast release_version "18") ''
-                substituteInPlace unittests/Support/VirtualFileSystemTest.cpp \
-                  --replace-fail "PhysicalFileSystemWorkingDirFailure" "DISABLED_PhysicalFileSystemWorkingDirFailure"
+                substituteInPlace unittests/TargetParser/Host.cpp \
+                  --replace-fail '/usr/bin/sw_vers' "${(builtins.toString darwin.DarwinTools) + "/bin/sw_vers"}"
               ''
-          ))
+            else
+              ''
+                substituteInPlace unittests/Support/Host.cpp \
+                  --replace-fail '/usr/bin/sw_vers' "${(builtins.toString darwin.DarwinTools) + "/bin/sw_vers"}"
+              ''
+          )
+        +
+          # This test tries to call the intrinsics `@llvm.roundeven.f32` and
+          # `@llvm.roundeven.f64` which seem to (incorrectly?) lower to `roundevenf`
+          # and `roundeven` on macOS and FreeBSD.
+          #
+          # However these functions are glibc specific so the test fails:
+          #   - https://www.gnu.org/software/gnulib/manual/html_node/roundevenf.html
+          #   - https://www.gnu.org/software/gnulib/manual/html_node/roundeven.html
+          #
+          # TODO(@rrbutani): this seems to run fine on `aarch64-darwin`, why does it
+          # pass there?
+          optionalString (lib.versionAtLeast release_version "16") ''
+            substituteInPlace test/ExecutionEngine/Interpreter/intrinsics.ll \
+              --replace-fail "%roundeven32 = call float @llvm.roundeven.f32(float 0.000000e+00)" "" \
+              --replace-fail "%roundeven64 = call double @llvm.roundeven.f64(double 0.000000e+00)" ""
+          ''
+        +
+          # fails when run in sandbox
+          optionalString (!stdenv.hostPlatform.isx86 && lib.versionAtLeast release_version "18") ''
+            substituteInPlace unittests/Support/VirtualFileSystemTest.cpp \
+              --replace-fail "PhysicalFileSystemWorkingDirFailure" "DISABLED_PhysicalFileSystemWorkingDirFailure"
+          ''
       )
       +
         # dup of above patch with different conditions
-        optionalString
-          (
-            stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86 && lib.versionAtLeast release_version "15"
-          )
-          (
-            optionalString (lib.versionOlder release_version "16") ''
-              substituteInPlace test/ExecutionEngine/Interpreter/intrinsics.ll \
-                --replace-fail "%roundeven32 = call float @llvm.roundeven.f32(float 0.000000e+00)" "" \
-                --replace-fail "%roundeven64 = call double @llvm.roundeven.f64(double 0.000000e+00)" ""
+        optionalString (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86) (
+          optionalString (lib.versionOlder release_version "16") ''
+            substituteInPlace test/ExecutionEngine/Interpreter/intrinsics.ll \
+              --replace-fail "%roundeven32 = call float @llvm.roundeven.f32(float 0.000000e+00)" "" \
+              --replace-fail "%roundeven64 = call double @llvm.roundeven.f64(double 0.000000e+00)" ""
 
-            ''
-            +
-              # fails when run in sandbox
-              (
-                (optionalString (lib.versionAtLeast release_version "18") ''
-                  substituteInPlace unittests/Support/VirtualFileSystemTest.cpp \
-                    --replace-fail "PhysicalFileSystemWorkingDirFailure" "DISABLED_PhysicalFileSystemWorkingDirFailure"
-                '')
-                +
-                  # This test fails on darwin x86_64 because `sw_vers` reports a different
-                  # macOS version than what LLVM finds by reading
-                  # `/System/Library/CoreServices/SystemVersion.plist` (which is passed into
-                  # the sandbox on macOS).
-                  #
-                  # The `sw_vers` provided by nixpkgs reports the macOS version associated
-                  # with the `CoreFoundation` framework with which it was built. Because
-                  # nixpkgs pins the SDK for `aarch64-darwin` and `x86_64-darwin` what
-                  # `sw_vers` reports is not guaranteed to match the macOS version of the host
-                  # that's building this derivation.
-                  #
-                  # Astute readers will note that we only _patch_ this test on aarch64-darwin
-                  # (to use the nixpkgs provided `sw_vers`) instead of disabling it outright.
-                  # So why does this test pass on aarch64?
-                  #
-                  # Well, it seems that `sw_vers` on aarch64 actually links against the _host_
-                  # CoreFoundation framework instead of the nixpkgs provided one.
-                  #
-                  # Not entirely sure what the right fix is here. I'm assuming aarch64
-                  # `sw_vers` doesn't intentionally link against the host `CoreFoundation`
-                  # (still digging into how this ends up happening, will follow up) but that
-                  # aside I think the more pertinent question is: should we be patching LLVM's
-                  # macOS version detection logic to use `sw_vers` instead of reading host
-                  # paths? This *is* a way in which details about builder machines can creep
-                  # into the artifacts that are produced, affecting reproducibility, but it's
-                  # not clear to me when/where/for what this even gets used in LLVM.
-                  #
-                  # TODO(@rrbutani): fix/follow-up
-                  (
-                    if lib.versionAtLeast release_version "16" then
-                      ''
-                        substituteInPlace unittests/TargetParser/Host.cpp \
-                          --replace-fail "getMacOSHostVersion" "DISABLED_getMacOSHostVersion"
-                      ''
-                    else
-                      ''
-                        substituteInPlace unittests/Support/Host.cpp \
-                          --replace-fail "getMacOSHostVersion" "DISABLED_getMacOSHostVersion"
-                      ''
-                  )
-                +
-                  # This test fails with a `dysmutil` crash; have not yet dug into what's
-                  # going on here (TODO(@rrbutani)).
-                  lib.optionalString (lib.versionOlder release_version "19") ''
-                    rm test/tools/dsymutil/ARM/obfuscated.test
-                  ''
-              )
-          )
+          ''
+          +
+            # fails when run in sandbox
+            (
+              (optionalString (lib.versionAtLeast release_version "18") ''
+                substituteInPlace unittests/Support/VirtualFileSystemTest.cpp \
+                  --replace-fail "PhysicalFileSystemWorkingDirFailure" "DISABLED_PhysicalFileSystemWorkingDirFailure"
+              '')
+              +
+                # This test fails on darwin x86_64 because `sw_vers` reports a different
+                # macOS version than what LLVM finds by reading
+                # `/System/Library/CoreServices/SystemVersion.plist` (which is passed into
+                # the sandbox on macOS).
+                #
+                # The `sw_vers` provided by nixpkgs reports the macOS version associated
+                # with the `CoreFoundation` framework with which it was built. Because
+                # nixpkgs pins the SDK for `aarch64-darwin` and `x86_64-darwin` what
+                # `sw_vers` reports is not guaranteed to match the macOS version of the host
+                # that's building this derivation.
+                #
+                # Astute readers will note that we only _patch_ this test on aarch64-darwin
+                # (to use the nixpkgs provided `sw_vers`) instead of disabling it outright.
+                # So why does this test pass on aarch64?
+                #
+                # Well, it seems that `sw_vers` on aarch64 actually links against the _host_
+                # CoreFoundation framework instead of the nixpkgs provided one.
+                #
+                # Not entirely sure what the right fix is here. I'm assuming aarch64
+                # `sw_vers` doesn't intentionally link against the host `CoreFoundation`
+                # (still digging into how this ends up happening, will follow up) but that
+                # aside I think the more pertinent question is: should we be patching LLVM's
+                # macOS version detection logic to use `sw_vers` instead of reading host
+                # paths? This *is* a way in which details about builder machines can creep
+                # into the artifacts that are produced, affecting reproducibility, but it's
+                # not clear to me when/where/for what this even gets used in LLVM.
+                #
+                # TODO(@rrbutani): fix/follow-up
+                (
+                  if lib.versionAtLeast release_version "16" then
+                    ''
+                      substituteInPlace unittests/TargetParser/Host.cpp \
+                        --replace-fail "getMacOSHostVersion" "DISABLED_getMacOSHostVersion"
+                    ''
+                  else
+                    ''
+                      substituteInPlace unittests/Support/Host.cpp \
+                        --replace-fail "getMacOSHostVersion" "DISABLED_getMacOSHostVersion"
+                    ''
+                )
+              +
+                # This test fails with a `dysmutil` crash; have not yet dug into what's
+                # going on here (TODO(@rrbutani)).
+                lib.optionalString (lib.versionOlder release_version "19") ''
+                  rm test/tools/dsymutil/ARM/obfuscated.test
+                ''
+            )
+        )
       +
         # FileSystem permissions tests fail with various special bits
         ''
@@ -438,11 +432,9 @@ stdenv.mkDerivation (
         )
       +
         # timing-based tests are trouble
-        lib.optionalString
-          (lib.versionAtLeast release_version "15" && lib.versionOlder release_version "17")
-          ''
-            rm utils/lit/tests/googletest-timeout.py
-          ''
+        lib.optionalString (lib.versionOlder release_version "17") ''
+          rm utils/lit/tests/googletest-timeout.py
+        ''
       +
         # valgrind unhappy with musl or glibc, but fails w/musl only
         optionalString stdenv.hostPlatform.isMusl ''
@@ -496,6 +488,40 @@ stdenv.mkDerivation (
       )
     '';
 
+    # Defensive check: some paths (that we make symlinks to) depend on the release
+    # version, for example:
+    #  - https://github.com/llvm/llvm-project/blob/406bde9a15136254f2b10d9ef3a42033b3cb1b16/clang/lib/Headers/CMakeLists.txt#L185
+    #
+    # So we want to sure that the version in the source matches the release
+    # version we were given.
+    #
+    # We do this check here, in the LLVM build, because it happens early.
+    postConfigure =
+      let
+        v = lib.versions;
+        major = v.major release_version;
+        minor = v.minor release_version;
+        patch = v.patch release_version;
+      in
+      ''
+        # $1: part, $2: expected
+        check_version() {
+          part="''${1^^}"
+          part="$(cat include/llvm/Config/llvm-config.h  | grep "#define LLVM_VERSION_''${part} " | cut -d' ' -f3)"
+
+          if [[ "$part" != "$2" ]]; then
+            echo >&2 \
+              "mismatch in the $1 version! we have version ${release_version}" \
+              "and expected the $1 version to be '$2'; the source has '$part' instead"
+            exit 3
+          fi
+        }
+
+        check_version major ${major}
+        check_version minor ${minor}
+        check_version patch ${patch}
+      '';
+
     # E.g. Mesa uses the build-id as a cache key (see #93946):
     LDFLAGS = optionalString (
       enableSharedLibraries && !stdenv.hostPlatform.isDarwin
@@ -512,22 +538,12 @@ stdenv.mkDerivation (
         #
         # Some flags don't need to be repassed because LLVM already does so (like
         # CMAKE_BUILD_TYPE), others are irrelevant to the result.
-        flagsForLlvmConfig =
-          (
-            if lib.versionOlder release_version "15" then
-              [
-                (lib.cmakeFeature "LLVM_INSTALL_CMAKE_DIR" "${placeholder "dev"}/lib/cmake/llvm/")
-              ]
-            else
-              [
-                (lib.cmakeFeature "LLVM_INSTALL_PACKAGE_DIR" "${placeholder "dev"}/lib/cmake/llvm")
-              ]
-          )
-          ++ [
-            (lib.cmakeBool "LLVM_ENABLE_RTTI" true)
-            (lib.cmakeBool "LLVM_LINK_LLVM_DYLIB" enableSharedLibraries)
-            (lib.cmakeFeature "LLVM_TABLEGEN" "${buildLlvmTools.tblgen}/bin/llvm-tblgen")
-          ];
+        flagsForLlvmConfig = [
+          (lib.cmakeFeature "LLVM_INSTALL_PACKAGE_DIR" "${placeholder "dev"}/lib/cmake/llvm")
+          (lib.cmakeBool "LLVM_ENABLE_RTTI" true)
+          (lib.cmakeBool "LLVM_LINK_LLVM_DYLIB" enableSharedLibraries)
+          (lib.cmakeFeature "LLVM_TABLEGEN" "${buildLlvmTools.tblgen}/bin/llvm-tblgen")
+        ];
       in
       flagsForLlvmConfig
       ++ [
@@ -617,19 +633,9 @@ stdenv.mkDerivation (
       moveToOutput "bin/llvm-config*" "$dev"
       substituteInPlace "$dev/lib/cmake/llvm/LLVMExports-${lib.toLower finalAttrs.finalPackage.cmakeBuildType}.cmake" \
         --replace-fail "$out/bin/llvm-config" "$dev/bin/llvm-config"
+      substituteInPlace "$dev/lib/cmake/llvm/LLVMConfig.cmake" \
+        --replace-fail 'set(LLVM_BINARY_DIR "''${LLVM_INSTALL_PREFIX}")' 'set(LLVM_BINARY_DIR "'"$lib"'")'
     ''
-    + (
-      if lib.versionOlder release_version "15" then
-        ''
-          substituteInPlace "$dev/lib/cmake/llvm/LLVMConfig.cmake" \
-            --replace-fail 'set(LLVM_BINARY_DIR "''${LLVM_INSTALL_PREFIX}")' 'set(LLVM_BINARY_DIR "''${LLVM_INSTALL_PREFIX}'"$lib"'")'
-        ''
-      else
-        ''
-          substituteInPlace "$dev/lib/cmake/llvm/LLVMConfig.cmake" \
-            --replace-fail 'set(LLVM_BINARY_DIR "''${LLVM_INSTALL_PREFIX}")' 'set(LLVM_BINARY_DIR "'"$lib"'")'
-        ''
-    )
     + optionalString (stdenv.hostPlatform.isDarwin && enableSharedLibraries) ''
       ln -s $lib/lib/libLLVM.dylib $lib/lib/libLLVM-${
         if lib.versionOlder release_version "18" then "$shortVersion" else release_version
@@ -649,7 +655,6 @@ stdenv.mkDerivation (
     doCheck =
       !isDarwinBootstrap
       && !stdenv.hostPlatform.isAarch32
-      && (if lib.versionOlder release_version "15" then stdenv.hostPlatform.isLinux else true)
       && (
         !stdenv.hostPlatform.isx86_32 # TODO: why
       )
@@ -682,92 +687,23 @@ stdenv.mkDerivation (
       '';
     };
   }
-  // lib.optionalAttrs enableManpages (
-    {
-      pname = "llvm-manpages";
+  // lib.optionalAttrs enableManpages {
+    pname = "llvm-manpages";
 
-      propagatedBuildInputs = [ ];
+    propagatedBuildInputs = [ ];
 
-      postPatch = null;
-      postInstall = null;
+    ninjaFlags = [ "docs-llvm-man" ];
+    installTargets = [ "install-docs-llvm-man" ];
 
-      outputs = [ "out" ];
+    doCheck = false;
 
-      doCheck = false;
+    postPatch = null;
+    postInstall = null;
 
-      meta = llvm_meta // {
-        description = "man pages for LLVM ${version}";
-      };
-    }
-    // (
-      if lib.versionOlder release_version "15" then
-        {
-          buildPhase = ''
-            make docs-llvm-man
-          '';
+    outputs = [ "out" ];
 
-          installPhase = ''
-            make -C docs install
-          '';
-        }
-      else
-        {
-          ninjaFlags = [ "docs-llvm-man" ];
-          installTargets = [ "install-docs-llvm-man" ];
-
-          postPatch = null;
-          postInstall = null;
-        }
-    )
-  )
-  // lib.optionalAttrs (lib.versionOlder release_version "15") {
-    # hacky fix: created binaries need to be run before installation
-    preBuild = ''
-      mkdir -p $out/
-      ln -sv $PWD/lib $out
-    '';
-
-    postBuild = ''
-      rm -fR $out
-    '';
-
-    preCheck = ''
-      export LD_LIBRARY_PATH=$LD_LIBRARY_PATH''${LD_LIBRARY_PATH:+:}$PWD/lib
-    '';
-  }
-  // lib.optionalAttrs (lib.versionAtLeast release_version "15") {
-    # Defensive check: some paths (that we make symlinks to) depend on the release
-    # version, for example:
-    #  - https://github.com/llvm/llvm-project/blob/406bde9a15136254f2b10d9ef3a42033b3cb1b16/clang/lib/Headers/CMakeLists.txt#L185
-    #
-    # So we want to sure that the version in the source matches the release
-    # version we were given.
-    #
-    # We do this check here, in the LLVM build, because it happens early.
-    postConfigure =
-      let
-        v = lib.versions;
-        major = v.major release_version;
-        minor = v.minor release_version;
-        patch = v.patch release_version;
-      in
-      ''
-        # $1: part, $2: expected
-        check_version() {
-          part="''${1^^}"
-          part="$(cat include/llvm/Config/llvm-config.h  | grep "#define LLVM_VERSION_''${part} " | cut -d' ' -f3)"
-
-          if [[ "$part" != "$2" ]]; then
-            echo >&2 \
-              "mismatch in the $1 version! we have version ${release_version}" \
-              "and expected the $1 version to be '$2'; the source has '$part' instead"
-            exit 3
-          fi
-        }
-
-        check_version major ${major}
-        check_version minor ${minor}
-        check_version patch ${patch}
-      '';
+    meta = llvm_meta // {
+      description = "man pages for LLVM ${version}";
+    };
   }
 )
diff --git a/pkgs/development/compilers/llvm/common/openmp/default.nix b/pkgs/development/compilers/llvm/common/openmp/default.nix
index de79d15be76c..8482417436fb 100644
--- a/pkgs/development/compilers/llvm/common/openmp/default.nix
+++ b/pkgs/development/compilers/llvm/common/openmp/default.nix
@@ -50,9 +50,7 @@ stdenv.mkDerivation (finalAttrs: {
   patchFlags = null;
 
   patches =
-    lib.optional (lib.versionAtLeast release_version "15" && lib.versionOlder release_version "19") (
-      getVersionFile "openmp/fix-find-tool.patch"
-    )
+    lib.optional (lib.versionOlder release_version "19") (getVersionFile "openmp/fix-find-tool.patch")
     ++ lib.optional (lib.versionOlder release_version "18") (
       getVersionFile "openmp/gnu-install-dirs.patch"
     )
@@ -64,11 +62,7 @@ stdenv.mkDerivation (finalAttrs: {
     cmake
     python3.pythonOnBuildForHost
     perl
-  ]
-  ++ lib.optionals (lib.versionAtLeast release_version "15") [
     ninja
-  ]
-  ++ [
     pkg-config
     lit
   ];
diff --git a/pkgs/development/compilers/llvm/common/patches.nix b/pkgs/development/compilers/llvm/common/patches.nix
index fdfe16a862ae..ce241bf33184 100644
--- a/pkgs/development/compilers/llvm/common/patches.nix
+++ b/pkgs/development/compilers/llvm/common/patches.nix
@@ -12,13 +12,8 @@
     }
     {
       before = "17";
-      after = "15";
       path = ../15;
     }
-    {
-      before = "16";
-      path = ../14;
-    }
   ];
   "clang/aarch64-tblgen.patch" = [
     {
@@ -72,13 +67,12 @@
     }
     {
       before = "18";
-      path = ../14;
+      path = ../15;
     }
   ];
   "llvm/llvm-lit-cfg-add-libs-to-dylib-path.patch" = [
     {
       before = "17";
-      after = "15";
       path = ../15;
     }
     {
@@ -99,26 +93,19 @@
   ];
   "llvm/polly-lit-cfg-add-libs-to-dylib-path.patch" = [
     {
-      after = "15";
       path = ../15;
     }
   ];
   "libunwind/gnu-install-dirs.patch" = [
     {
       before = "17";
-      after = "15";
       path = ../15;
     }
   ];
   "compiler-rt/X86-support-extension.patch" = [
     {
-      after = "15";
       path = ../15;
     }
-    {
-      before = "15";
-      path = ../14;
-    }
   ];
   "compiler-rt/armv6-scudo-libatomic.patch" = [
     {
@@ -126,28 +113,12 @@
       path = ../19;
     }
     {
-      after = "15";
       before = "19";
       path = ../15;
     }
-    {
-      before = "15";
-      path = ../14;
-    }
-  ];
-  "compiler-rt/armv7l.patch" = [
-    {
-      before = "15";
-      path = ../14;
-    }
   ];
   "compiler-rt/gnu-install-dirs.patch" = [
     {
-      before = "15";
-      path = ../14;
-    }
-    {
-      after = "15";
       before = "17";
       path = ../15;
     }
@@ -158,12 +129,7 @@
   ];
   "compiler-rt/darwin-targetconditionals.patch" = [
     {
-      path = ../14;
-    }
-  ];
-  "compiler-rt/codesign.patch" = [
-    {
-      path = ../14;
+      path = ../15;
     }
   ];
   "compiler-rt/normalize-var.patch" = [
@@ -173,29 +139,24 @@
     }
     {
       before = "16";
-      path = ../14;
+      path = ../15;
     }
   ];
   "lldb/procfs.patch" = [
     {
-      after = "15";
       path = ../15;
     }
-    {
-      before = "15";
-      path = ../14;
-    }
   ];
   "lldb/resource-dir.patch" = [
     {
       before = "16";
-      path = ../14;
+      path = ../15;
     }
   ];
   "llvm/no-pipes.patch" = [
     {
       before = "16";
-      path = ../14;
+      path = ../15;
     }
   ];
   "openmp/fix-find-tool.patch" = [
@@ -212,7 +173,7 @@
     }
     {
       before = "16";
-      path = ../14;
+      path = ../15;
     }
   ];
   "libclc/use-default-paths.patch" = [
diff --git a/pkgs/development/compilers/llvm/common/tblgen.nix b/pkgs/development/compilers/llvm/common/tblgen.nix
index cdf99dcca5c5..c1b725be279f 100644
--- a/pkgs/development/compilers/llvm/common/tblgen.nix
+++ b/pkgs/development/compilers/llvm/common/tblgen.nix
@@ -54,18 +54,14 @@ let
   targets = [
     "clang-tblgen"
     "llvm-tblgen"
-  ]
-  ++ lib.optionals (lib.versionAtLeast release_version "15") [
     "clang-tidy-confusable-chars-gen"
   ]
   ++ lib.optionals (lib.versionAtLeast release_version "16") [
     "mlir-tblgen"
   ]
-  ++
-    lib.optionals ((lib.versionAtLeast release_version "15") && (lib.versionOlder release_version "20"))
-      [
-        "clang-pseudo-gen" # Removed in LLVM 20 @ ed8f78827895050442f544edef2933a60d4a7935.
-      ];
+  ++ lib.optionals (lib.versionOlder release_version "20") [
+    "clang-pseudo-gen" # Removed in LLVM 20 @ ed8f78827895050442f544edef2933a60d4a7935.
+  ];
 
   self = stdenv.mkDerivation (finalAttrs: {
     inherit pname version patches;
diff --git a/pkgs/development/compilers/llvm/default.nix b/pkgs/development/compilers/llvm/default.nix
index e678cfd236f0..19f8901f2bdc 100644
--- a/pkgs/development/compilers/llvm/default.nix
+++ b/pkgs/development/compilers/llvm/default.nix
@@ -22,7 +22,6 @@
 }@packageSetArgs:
 let
   versions = {
-    "14.0.6".officialRelease.sha256 = "sha256-vffu4HilvYwtzwgq+NlS26m65DGbp6OSSne2aje1yJE=";
     "15.0.7".officialRelease.sha256 = "sha256-wjuZQyXQ/jsmvy6y1aksCcEDXGBjuhpgngF3XQJ/T4s=";
     "16.0.6".officialRelease.sha256 = "sha256-fspqSReX+VD+Nl/Cfq+tDcdPtnQPV1IRopNDfd5VtUs=";
     "17.0.6".officialRelease.sha256 = "sha256-8MEDLLhocshmxoEBRSKlJ/GzJ8nfuzQ8qn0X/vLA+ag=";
diff --git a/pkgs/test/default.nix b/pkgs/test/default.nix
index 14fe49af40f4..25c23371c565 100644
--- a/pkgs/test/default.nix
+++ b/pkgs/test/default.nix
@@ -18,6 +18,7 @@ with pkgs;
             (filter (n: n != "llvmPackages_11"))
             (filter (n: n != "llvmPackages_12"))
             (filter (n: n != "llvmPackages_13"))
+            (filter (n: n != "llvmPackages_14"))
           ];
           tests = lib.genAttrs pkgSets (
             name:
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 005436eeaa74..75fd28c94099 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -698,14 +698,12 @@ mapAliases {
   cyber = throw "cyber has been removed, as it does not build with supported Zig versions"; # Added 2025-08-09
 
   # these are for convenience, not for backward compat., and shouldn't expire until the package is deprecated.
-  clang14Stdenv = lowPrio llvmPackages_14.stdenv; # preserve, reason: see above
   clang15Stdenv = lowPrio llvmPackages_15.stdenv; # preserve, reason: see above
   clang16Stdenv = lowPrio llvmPackages_16.stdenv; # preserve, reason: see above
   clang17Stdenv = lowPrio llvmPackages_17.stdenv; # preserve, reason: see above
   clang18Stdenv = lowPrio llvmPackages_18.stdenv; # preserve, reason: see above
   clang19Stdenv = lowPrio llvmPackages_19.stdenv; # preserve, reason: see above
 
-  clang-tools_14 = llvmPackages_14.clang-tools; # Added 2024-04-22
   clang-tools_15 = llvmPackages_15.clang-tools; # Added 2024-04-22
   clang-tools_16 = llvmPackages_16.clang-tools; # Added 2024-04-22
   clang-tools_17 = llvmPackages_17.clang-tools; # Added 2024-04-22
@@ -1501,6 +1499,14 @@ mapAliases {
   clang13Stdenv = throw "clang13Stdenv has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
   clang-tools_13 = throw "clang-tools_13 has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
 
+  llvmPackages_14 = throw "llvmPackages_14 has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
+  llvm_14 = throw "llvm_14 has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
+  lld_14 = throw "lld_14 has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
+  lldb_14 = throw "lldb_14 has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
+  clang_14 = throw "clang_14 has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
+  clang14Stdenv = throw "clang14Stdenv has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
+  clang-tools_14 = throw "clang-tools_14 has been removed, as it is unmaintained and obsolete"; # Added 2025-08-10
+
   lobster-two = throw "'lobster-two' has been renamed to/replaced by 'google-fonts'"; # Converted to throw 2024-10-17
   loc = throw "'loc' has been removed due to lack of upstream maintenance. Consider 'tokei' as an alternative."; # Added 2025-01-25
   loco-cli = loco; # Added 2025-02-24
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 22b22ea3414e..31584910c6f6 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -4633,7 +4633,6 @@ with pkgs;
   clang-manpages = llvmPackages.clang-manpages;
 
   clang = llvmPackages.clang;
-  clang_14 = llvmPackages_14.clang;
   clang_15 = llvmPackages_15.clang;
   clang_16 = llvmPackages_16.clang;
   clang_17 = llvmPackages_17.clang;
@@ -5363,19 +5362,16 @@ with pkgs;
   };
 
   lld = llvmPackages.lld;
-  lld_14 = llvmPackages_14.lld;
   lld_15 = llvmPackages_15.lld;
   lld_16 = llvmPackages_16.lld;
   lld_17 = llvmPackages_17.lld;
 
   lldb = llvmPackages.lldb;
-  lldb_14 = llvmPackages_14.lldb;
   lldb_15 = llvmPackages_15.lldb;
   lldb_16 = llvmPackages_16.lldb;
   lldb_17 = llvmPackages_17.lldb;
 
   llvm = llvmPackages.llvm;
-  llvm_14 = llvmPackages_14.llvm;
   llvm_15 = llvmPackages_15.llvm;
   llvm_16 = llvmPackages_16.llvm;
   llvm_17 = llvmPackages_17.llvm;
@@ -5394,7 +5390,6 @@ with pkgs;
     (rec {
       llvmPackagesSet = recurseIntoAttrs (callPackages ../development/compilers/llvm { });
 
-      llvmPackages_14 = llvmPackagesSet."14";
       llvmPackages_15 = llvmPackagesSet."15";
       llvmPackages_16 = llvmPackagesSet."16";
       llvmPackages_17 = llvmPackagesSet."17";
@@ -5430,7 +5425,6 @@ with pkgs;
 
       mkLLVMPackages = llvmPackagesSet.mkPackage;
     })
-    llvmPackages_14
     llvmPackages_15
     llvmPackages_16
     llvmPackages_17