llvm-rc got support for this option on Jun 23rd [1], so the currently pinned version of llvm-project doesn't support it - but earlier versions just silently ignore the option, so it should be safe to include in the wrapper now already. [1] https://github.com/llvm/llvm-project/commit/f36f8b41beb9cc0353d5624934406d39b78753e0