diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index bc9c199f778d..77ecaf098eac 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -364,9 +364,9 @@ stdenv.mkDerivation {
     ''
     # this ensures that when clang passes -lgcc_s to lld (as it does
     # when building e.g. firefox), lld is able to find libgcc_s.so
-    + lib.optionalString (gccForLibs?libgcc) ''
-      echo "-L${gccForLibs.libgcc}/lib" >> $out/nix-support/cc-ldflags
-    '')
+    + concatMapStrings (libgcc: ''
+      echo "-L${libgcc}/lib" >> $out/nix-support/cc-ldflags
+    '') (lib.toList (gccForLibs.libgcc or [])))
 
     ##
     ## General libc support
diff --git a/pkgs/development/compilers/llvm/multi.nix b/pkgs/development/compilers/llvm/multi.nix
index ecea5d440378..136e13ba21f5 100644
--- a/pkgs/development/compilers/llvm/multi.nix
+++ b/pkgs/development/compilers/llvm/multi.nix
@@ -28,7 +28,9 @@ let
 
 
     # includes
-    ln -s ${glibc_multi.dev}/include $out/
+    mkdir -p $out/include
+    ln -s ${glibc_multi.dev}/include/* $out/include
+    ln -s ${gcc64.cc}/include/c++ $out/include/c++
 
     # dynamic linkers
     mkdir -p $out/lib/32
@@ -46,7 +48,13 @@ let
       libc = gcc_multi_sysroot;
     };
 
-    gccForLibs = gcc_multi_sysroot;
+    gccForLibs = gcc_multi_sysroot // {
+      inherit (glibc_multi) libgcc;
+      langCC =
+        assert (gcc64.cc.langCC != gcc32.cc.langCC)
+               -> throw "(gcc64.cc.langCC=${gcc64.cc.langCC}) != (gcc32.cc.langCC=${gcc32.cc.langCC})";
+        gcc64.cc.langCC;
+    };
   };
 
 in clangMulti
diff --git a/pkgs/development/libraries/glibc/multi.nix b/pkgs/development/libraries/glibc/multi.nix
index be190d77c736..5cd48958ec2c 100644
--- a/pkgs/development/libraries/glibc/multi.nix
+++ b/pkgs/development/libraries/glibc/multi.nix
@@ -1,4 +1,5 @@
-{ runCommand, glibc, glibc32
+{ lib
+, runCommand, glibc, glibc32
 }:
 
 let
@@ -7,7 +8,15 @@ let
 in
 runCommand "${nameVersion.name}-multi-${nameVersion.version}"
   # out as the first output is an exception exclusive to glibc
-  { outputs = [ "out" "bin" "dev" ]; } # TODO: no static version here (yet)
+  {
+    outputs = [ "out" "bin" "dev" ];  # TODO: no static version here (yet)
+    passthru = {
+      libgcc = lib.lists.filter (x: x!=null) [
+        (glibc64.libgcc or null)
+        (glibc32.libgcc or null)
+      ];
+    };
+  }
   ''
     mkdir -p "$out/lib"
     ln -s '${glibc64.out}'/lib/* "$out/lib"