If you missed out on LLVM/Clang 3.8 features, see our feature overview. Aside from all the traditional compiler improvements, LLVM 3.8 is also exciting for AMDGPU users as being an important update for those using the AMD open-source Linux graphics driver stack.
Today's release announcement by Google's Hans Wennborg mentions their proud-of highlights including "deprecated autoconf build, shrink-wrapping on by default, overhauled MSVC-compatible exception handling, updated Kaleidoscope tutorial, emutls, OpenMP supported by default, as well as improved optimizations, many bug fixes, and more."
We've published many LLVM/Clang 3.8 benchmarks on Phoronix along with the daily automated tests on LinuxBenchmarking.com (though temporarily halted due to still the broken llvm.org/apt builds) while more will be on the way. LLVM Clang 3.9 is also already in development.