As far as I understand, Visual Studio 2015 is shipped with clang. First I though this was only for Android and iOS apps, but according to this article it should also be possible
After reading through the linked post and especially the comments again, I came to understand, that this is not a feature shipped with VS2015 RC but a possible future feature that might e.g. be shipped in a SP or (more likely) with the next version of VS.
As mentioned by sjdowling, the closest thing you can do at the moment (October 2015, clang 3.7) is to download and install llvm for windows. This should give you a LLVM-vs2014 platform toolset option. For me it works for simple test programs, but apparently this version of "clang-vs" seems to not yet support exceptions. However, according to these notes, that problem should be mostly solved for clang 3.8.