Rustc does, but it doesn't appear to me that holyjit does, that is https://github.com/nbp/holyjit/blob/master/lib/src/compile.r... and https://github.com/nbp/holyjit/blob/master/lib/src/lib.rs#L1...

Basically, it seems (and I haven't fully digested the code yet) that it uses https://crates.io/crates/dynasmrt for codegen.