Intel and others have long been working on OpenMP support for LLVM and Clang going back years, with out-of-tree code being available but never mainlined up to this point. We've been looking at the prospects of OpenMP for Clang as it's one of the last few areas where GCC has a big advantage over Clang with many scientific and HPC codes using this multi-platform, shared memory multi-processing API.
An LLVM stakeholder had asked about the OpenMP support for LLVM/Clang 3.5 following the news that LLVM 3.5 is being planned for an August release. Bill Wendling of Apple who generally arranges the testing around new LLVM releases, stated, "I didn’t have any specific plans for OpenMP in the release. If you’d be willing to test and build for OpenMP, then we could release it. :-)"
Those wishing to try out Intel's out-of-tree LLVM Clang OpenMP support can see their GitHub repository. I'll try to get up some fresh benchmarks of the Clang vs. GCC support for this multi-processing API in short order.