I can't seem to get the patch to apply, could you please regenerate it against a fresh checkout of https://hg.python.org/cpython#default (or 'master' of github.com/python/cpython)?

This looks fairly straightforward, but I'm far from an expert on distutils :).  I can see issues arising from attempts to use a compiler/linker/etc. that doesn't recognize options that we assume are going to cl/link/etc., but I'm not sure how big a deal that is: I'd be inclined to say that if you're trying to tell distutils where cl is, don't get mad when what you told it doesn't work.

Also, I don't think Lib/distutils/msvccompiler.py is used anymore, but rather Lib/distutils/_msvccompiler.py in 3.5+.

I'm generally in favor of this, but would feel much better about it with buy-in from Steve.

There has also been mention of creating a new ICCCompiler class, but I'm not sure whether that has gotten anywhere.