Both clang-8.0 and clang-9.0 having been building properly for us on the buildbots and (when I last did it) locally for me, on ElCap.
See <https://ports.macports.org/port/clang-9.0/summary> and the one for clang-8.0. But your logic is flawed about why you want it, as no clang version provides a macOS SDK, those come with either XCode or the Command Line Tools which you install separately from Apple. If you have a build error with clang 8 or 9, open a ticket and include your log, and we'll what might be wrong. Bes;t Ken
