diff --git a/pkgs/development/compilers/llvm/12/compiler-rt/darwin-targetconditionals.patch b/pkgs/development/compilers/llvm/12/compiler-rt/darwin-targetconditionals.patch
deleted file mode 100644
index 425dc2af01e7..000000000000
--- a/pkgs/development/compilers/llvm/12/compiler-rt/darwin-targetconditionals.patch
+++ /dev/null
@@ -1,71 +0,0 @@
-diff --git a/lib/sanitizer_common/sanitizer_mac.cpp b/lib/sanitizer_common/sanitizer_mac.cpp
---- a/lib/sanitizer_common/sanitizer_mac.cpp
-+++ b/lib/sanitizer_common/sanitizer_mac.cpp
-@@ -613,9 +613,15 @@ HandleSignalMode GetHandleSignalMode(int signum) {
- // Offset example:
- // XNU 17 -- macOS 10.13 -- iOS 11 -- tvOS 11 -- watchOS 4
- constexpr u16 GetOSMajorKernelOffset() {
--  if (TARGET_OS_OSX) return 4;
--  if (TARGET_OS_IOS || TARGET_OS_TV) return 6;
--  if (TARGET_OS_WATCH) return 13;
-+#if TARGET_OS_OSX
-+  return 4;
-+#endif
-+#if TARGET_OS_IOS || TARGET_OS_TV
-+  return 6;
-+#endif
-+#if TARGET_OS_WATCH
-+  return 13;
-+#endif
- }
- 
- using VersStr = char[64];
-@@ -627,13 +633,13 @@ static uptr ApproximateOSVersionViaKernelVersion(VersStr vers) {
-   u16 os_major = kernel_major - offset;
- 
-   const char *format = "%d.0";
--  if (TARGET_OS_OSX) {
--    if (os_major >= 16) {  // macOS 11+
--      os_major -= 5;
--    } else {  // macOS 10.15 and below
--      format = "10.%d";
--    }
-+#if TARGET_OS_OSX
-+  if (os_major >= 16) {  // macOS 11+
-+    os_major -= 5;
-+  } else {  // macOS 10.15 and below
-+    format = "10.%d";
-   }
-+#endif
-   return internal_snprintf(vers, sizeof(VersStr), format, os_major);
- }
- 
-@@ -681,15 +687,14 @@ void ParseVersion(const char *vers, u16 *major, u16 *minor) {
- // Aligned versions example:
- // macOS 10.15 -- iOS 13 -- tvOS 13 -- watchOS 6
- static void MapToMacos(u16 *major, u16 *minor) {
--  if (TARGET_OS_OSX)
--    return;
--
--  if (TARGET_OS_IOS || TARGET_OS_TV)
-+#if !TARGET_OS_OSX
-+#if TARGET_OS_IOS || TARGET_OS_TV
-     *major += 2;
--  else if (TARGET_OS_WATCH)
-+#elif TARGET_OS_WATCH
-     *major += 9;
--  else
-+#else
-     UNREACHABLE("unsupported platform");
-+#endif
- 
-   if (*major >= 16) {  // macOS 11+
-     *major -= 5;
-@@ -697,6 +702,7 @@ static void MapToMacos(u16 *major, u16 *minor) {
-     *minor = *major;
-     *major = 10;
-   }
-+#endif
- }
- 
- static MacosVersion GetMacosAlignedVersionInternal() {
diff --git a/pkgs/development/compilers/llvm/12/compiler-rt/default.nix b/pkgs/development/compilers/llvm/12/compiler-rt/default.nix
index fdc134bdf4b1..a3366468b75b 100644
--- a/pkgs/development/compilers/llvm/12/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/12/compiler-rt/default.nix
@@ -59,8 +59,6 @@ stdenv.mkDerivation {
     # extra `/`.
     ./normalize-var.patch
   ]# ++ lib.optional stdenv.hostPlatform.isMusl ./sanitizers-nongnu.patch
-    # Prevent a compilation error on darwin
-    ++ lib.optional stdenv.hostPlatform.isDarwin ./darwin-targetconditionals.patch
     ++ lib.optional stdenv.hostPlatform.isAarch32 ./armv7l.patch;
 
   # TSAN requires XPC on Darwin, which we have no public/free source files for. We can depend on the Apple frameworks
diff --git a/pkgs/os-specific/darwin/apple-source-releases/Libsystem/default.nix b/pkgs/os-specific/darwin/apple-source-releases/Libsystem/default.nix
index cb85566b5128..66190b7b4e37 100644
--- a/pkgs/os-specific/darwin/apple-source-releases/Libsystem/default.nix
+++ b/pkgs/os-specific/darwin/apple-source-releases/Libsystem/default.nix
@@ -69,7 +69,13 @@ appleDerivation' stdenv {
     #define TARGET_OS_UNIX          0
     #define TARGET_OS_EMBEDDED      0
     #define TARGET_OS_IPHONE        0
+    #define TARGET_OS_IOS           0
+    #define TARGET_OS_WATCH         0
+    #define TARGET_OS_BRIDGE        0
+    #define TARGET_OS_TV            0
+    #define TARGET_OS_SIMULATOR     0
     #define TARGET_IPHONE_SIMULATOR 0
+    #define TARGET_OS_NANO          0
     #define TARGET_OS_LINUX         0
 
     #define TARGET_CPU_PPC          0