Using musl may work. Rustc ships musl's libc.a together with libstd for x86_64-unknown-linux-musl.
Rust's lld is shipped on macOS. Lld doesn't really support compiling for macOS right now AFAIK, but I would expect it to support compiling on macOS for other targets. You still need a gcc or clang that knows which flags to pass to the linker to compile for linux though. -Clinker=clang -Clink-args="-target x86_64-unknown-linux-musl" --target x86_64-unknown-linux-musl -Zgcc-ld=lld may work on nightly. I haven't tested this at all though.
Indeed