[sirwhinesalot]

The only alternative I'm aware of with a similar level of optimization is GCC's backend, which is just as slow.

Both should be much faster at compiling debug builds than they are though. There's an LLVM fork (TPDE-LLVM) that supports a limited set of backend targets but compiles way faster (order of magnitude) for O0, but for whatever reason they haven't managed to merge it with the mainline LLVM. Even with that there's still plenty of overhead from all the horrible C++ OOP-brained abstractions LLVM uses.