After some more experimenting I've realized that the linking errors happen even in a completely fresh project the moment you call the ExecuteCompilerInvocation function.
I've uploaded a simple VS2013 solution/project that should make the problem easily reproducible here:
https://dl.dropboxusercontent.com/u/1735585/Win32Project1.rar
I would really appreciate it if someone using VS2013 could attempt to build it using the head revision of clang/llvm and see if you can reproduce the problem. You just need to change the includes to point to your own fresh clang/llvm source folders and build folder and change the library directory location.
Steps to reproduce:
Created fresh checkout folder for clang
Created fresh checkout folder for LLVM
Ran Cmake to generate fresh LLVM project files
Compiled LLVM + clang without problems
Created fresh win32 project in VS2013
Add clang/llvm includes and lib directory under debug config
Call ExecuteCompilerInvocation function in source code (if you comment out this call it links without errors)
Thank you very much for your time