llvm 3.7 is the first release that can build large projects such as Chromium on Windows without having to fall back to Visual Studio's compiler for a single translation unit. This talk gives an overview of the work done to get to this state: It covers language extensions clang needed to learn to parse Microsoft's headers and dark corners of the Microsoft ABI, with a focus on work done in the last year. Much of the Windows support was developed in tight collaboration between the Chromium and LLVM projects. The talk also touches on how this collaboration works and why it’s successful. Finally, the talk also gives an overview of how to get projects building with clang that build with Visual Studio.