gcc based Swift

Swift is an LLVM-based language, like Clang, with the caveat that it's not part of the LLVM project, but the Swift project, so LLVM is forked and included as part of the whole toolchain (including its own clang, lldb, etc.). So the original post has the right idea, but until the tables are turned and Swift is actually part of the LLVM project, which may or may not ever happen, it'll always be its own special thing.

Also, as mentioned, that's the language but does not take into account frameworks, certainly no GUI-based frameworks, which would be out of scope for LLVM.