I did in fact, use warpdrive, which uses those predefines, as you can see in the commands.

I'm also familiar with the innerworkings on llvm and gcc (having hacked a lot on both), and generated the list of include paths i used with warpdrive (emulating gcc 4.8.1) to be exactly the same as GCC on my system uses for 4.8.1.

I also verified the preprocessed output is "sane" in each case, as per diff.