I used Clang 3.1 to compile some small C programs on Windows, and the only problem I ran into was Clang defaulting the search paths based on the compiler used to build Clang itself. So, kind of goofy that Clang usage depends on whether you used MinGW or MSVC to build it (why isn't it compiling itself, anyway?), but easy enough to work around by adding the search paths on the command line.