Hi. clang --help tells about -cxx-abi parameter, but it not works: $ clang -cxx-abi microsoft foo.cpp clang: warning: argument unused during compilation: '-cxx-abi microsoft' Instead of it, you need to pass this option to CC1 directly: $ clang -Xclang -cxx-abi -Xclang microsoft But this is not equal with help. So how to fix?