On Microsoft Windows with VC 11.0, msvs.py assumes cl.exe is in the following directory:
C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\bin\amd64
However, things changed on VC 11.0 and now compiler binaries for AMD64 are under:
C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\bin\x86_amd64
Notice the change in the last component of the directory.
I can commit a patch, but I would like to study the source first so that my solution is elegant and compatible with how mbuild works. If you have a faster solution for this let me know :)