How to run lit tests on Mac OSX without gcc?

[Thomas Mader via digitalmars-d-ldc]

I am successfully building ldc 1.3.0 on Mac and running the 
phobos and druntime tests work too but I get the following error 
in the lit tests:

1561: $ "/tmp/nix-build-ldc-1.3.0.drv-1/build/bin/ldc2" 
"-cache=/private/tmp/nix-build-ldc-1.3.0.drv-1/build/tests/linking/Output/flag1cache" "-vv" "-run" "/private/tmp/nix-build-ldc-1.3.0.drv-1/tests/linking/ir2obj_caching_flags1.d"
1561: # command stderr:
1561: Error: failed to locate gcc
1561:
1561: error: command failed with exit status: 1
1561: $ "FileCheck" "--check-prefix=COULD_HIT" 
"/private/tmp/nix-build-ldc-1.3.0.drv-1/tests/linking/ir2obj_caching_flags1.d"

There is no gcc on this system. Is it possible to get the lit 
tests running without gcc as linker?
Everything else is built and run with clang.