diff --git a/pkgs/development/compilers/llvm/10/compiler-rt/default.nix b/pkgs/development/compilers/llvm/10/compiler-rt/default.nix
index 15fb0a7b9109..1f990ac433d2 100644
--- a/pkgs/development/compilers/llvm/10/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/10/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation rec {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -81,7 +80,9 @@ stdenv.mkDerivation rec {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/crtbeginS.o
diff --git a/pkgs/development/compilers/llvm/11/compiler-rt/default.nix b/pkgs/development/compilers/llvm/11/compiler-rt/default.nix
index 5ec37508c5e8..257bc34092fe 100644
--- a/pkgs/development/compilers/llvm/11/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/11/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation rec {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -84,7 +83,9 @@ stdenv.mkDerivation rec {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/crtbeginS.o
diff --git a/pkgs/development/compilers/llvm/12/compiler-rt/default.nix b/pkgs/development/compilers/llvm/12/compiler-rt/default.nix
index 7126deb8f0aa..b880a0071b9e 100644
--- a/pkgs/development/compilers/llvm/12/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/12/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation rec {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -84,7 +83,9 @@ stdenv.mkDerivation rec {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/crtbeginS.o
diff --git a/pkgs/development/compilers/llvm/5/compiler-rt/default.nix b/pkgs/development/compilers/llvm/5/compiler-rt/default.nix
index 237cea11a7ce..7e85c420da03 100644
--- a/pkgs/development/compilers/llvm/5/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/5/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -78,7 +77,9 @@ stdenv.mkDerivation {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/linux/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/linux/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/linux/crtbeginS.o
diff --git a/pkgs/development/compilers/llvm/6/compiler-rt/default.nix b/pkgs/development/compilers/llvm/6/compiler-rt/default.nix
index c74693629d31..384305f5cf28 100644
--- a/pkgs/development/compilers/llvm/6/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/6/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -80,7 +79,9 @@ stdenv.mkDerivation {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/linux/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/linux/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/linux/crtbeginS.o
diff --git a/pkgs/development/compilers/llvm/7/compiler-rt/default.nix b/pkgs/development/compilers/llvm/7/compiler-rt/default.nix
index d083347dde5c..75d61a51e601 100644
--- a/pkgs/development/compilers/llvm/7/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/7/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -81,7 +80,9 @@ stdenv.mkDerivation {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/linux/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/linux/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/linux/crtbeginS.o
diff --git a/pkgs/development/compilers/llvm/8/compiler-rt/default.nix b/pkgs/development/compilers/llvm/8/compiler-rt/default.nix
index 0f07e78ddedc..d370de031bb5 100644
--- a/pkgs/development/compilers/llvm/8/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/8/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -81,7 +80,9 @@ stdenv.mkDerivation {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/crtbeginS.o
diff --git a/pkgs/development/compilers/llvm/9/compiler-rt/default.nix b/pkgs/development/compilers/llvm/9/compiler-rt/default.nix
index f6f5a9cf8064..285fe811514f 100644
--- a/pkgs/development/compilers/llvm/9/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/9/compiler-rt/default.nix
@@ -21,7 +21,6 @@ stdenv.mkDerivation rec {
   ];
 
   cmakeFlags = [
-    "-DCOMPILER_RT_OS_DIR="
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
     "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
     "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
@@ -80,7 +79,9 @@ stdenv.mkDerivation rec {
   '';
 
   # Hack around weird upsream RPATH bug
-  postInstall = lib.optionalString (useLLVM) ''
+  postInstall = lib.optionalString (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isWasm) ''
+    ln -s "$out/lib"/*/* "$out/lib"
+  '' + lib.optionalString (useLLVM) ''
     ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/crtbegin.o
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/crtbeginS.o