As per the title. When you write llvm-ml.exe @foo.rsp you will get an error stating that @foo.rsp is not a valid file. While ml64.exe does not mention that it supports response files in its /help output, it actually does and when you do a CMake build for example using ASM_MASM as the language, it will pass response files to ml64.exe. So this means that llvm-ml.exe cannot be used with CMake since it will try to call llvm-ml with a response file, and I cannot find a way to disable this behavior.