How to dump help for mllvm option?

Hi, I added an option into llvm using cl::opt, it looks like below

enum class MyTestPointTy { MTP_First, MTP_Last, MTP_Default };
static cl::opt<MyTestPointTy> MTPoint(
    "mtp",
    cl::init(::MyTestPointTy::MTP_Default),
    cl::NotHidden,
    cl::desc("this is a test option for llvm")
);

How do I dump help message for the test option mtp using clang? I have searched with google and got few results, one result is from here. I have tried with /path/to/build/bin/clang -v --help-hidden -mllvm or /path/to/build/bin/clang -v --help -mllvm , nothing help is related to mtp option.

-mllvm -help

@Naville Not work. clang++ -mllvm -help prints error: no input files

-mllvm just forwards its argument on to the backend (ish), so you need a Clang command that’s valid enough to get that far. Try clang++ -mllvm -help -x c -c /dev/null for example.

@jrtc27 Thank you, it works!