On Mac OS, if I run clang --version, I get:
clang --version
Apple LLVM version 6.0 (clang-600.0.34.4) (based on LLVM 3.5svn) Target: x86_64-apple-darwin14.0.0 T
It is some Version of the llvm 3.5 svn branch before the official 3.5 release version.
Meaning that it probably should have all features of 3.4 plus some of the 3.5 features.