One key thing is missing from your comment (which explains the 'weirdness') - clang, and other llvm-family tools are cross-compatible by default. There is no separate cross compilation binary. This is just a configuration bug.
Yes, that's true, although it doesn't actually explain the weirdness. I compile Clang all the time and there's no obvious reason why you'd get cross-compiled binaries out of Clang if you just compile and install it normally. The bug, configuration or otherwise, is the weirdness.