The 'CodeGenObjC/illegal-UTF8.m' get failed with Clang built with 32-bit targets only (as example ARM-only) with the following error:
error: unable to create target: 'No available targets are compatible with triple "< ... any 64-bit target triple ... >"'
I didn't find any 64-bit dependencies for the test and I think removing '-m64' option should fix the problem and allow this test for any target specified by LLVM_DEFAULT_TARGET_TRIPLE.