diff --git a/pkgs/development/compilers/llvm/7/libc++abi/default.nix b/pkgs/development/compilers/llvm/7/libc++abi/default.nix
index 9f9606f586c..4f29ca0d6e2 100644
--- a/pkgs/development/compilers/llvm/7/libc++abi/default.nix
+++ b/pkgs/development/compilers/llvm/7/libc++abi/default.nix
@@ -1,5 +1,6 @@
 { lib, stdenv, cmake, fetch, libcxx, libunwind, llvm, version
 , standalone ? stdenv.hostPlatform.useLLVM or false
+, withLibunwind ? !stdenv.isDarwin && !stdenv.isFreeBSD && !stdenv.hostPlatform.isWasm
   # on musl the shared objects don't build
 , enableShared ? !stdenv.hostPlatform.isStatic
 }:
@@ -11,7 +12,13 @@ stdenv.mkDerivation {
   src = fetch "libcxxabi" "1zcqxsdjhawgz1cvpk07y3jl6fg9p3ay4nl69zsirqb2ghgyhhb2";
 
   nativeBuildInputs = [ cmake ];
-  buildInputs = lib.optional (!stdenv.isDarwin && !stdenv.isFreeBSD && !stdenv.hostPlatform.isWasm) libunwind;
+  buildInputs = lib.optional withLibunwind libunwind;
+
+  cmakeFlags = lib.optionals standalone [
+    "-DLLVM_ENABLE_LIBCXX=ON"
+  ] ++ lib.optionals (standalone && withLibunwind) [
+    "-DLIBCXXABI_USE_LLVM_UNWINDER=ON"
+  ] ++ lib.optional (!enableShared) "-DLIBCXXABI_ENABLE_SHARED=OFF";
 
   postUnpack = ''
     unpackFile ${libcxx.src}
@@ -23,11 +30,6 @@ stdenv.mkDerivation {
     patch -p1 -d $(ls -d libcxx-*) -i ${../../libcxx-0001-musl-hacks.patch}
   '';
 
-  cmakeFlags = lib.optionals standalone [
-    "-DLLVM_ENABLE_LIBCXX=ON"
-    "-DLIBCXXABI_USE_LLVM_UNWINDER=ON"
-  ] ++ lib.optional (!enableShared) "-DLIBCXXABI_ENABLE_SHARED=OFF";
-
   installPhase = if stdenv.isDarwin
     then ''
       for file in lib/*.dylib; do