Published this week have already been GCC 4.7/4.8 vs. LLVM/Clang 3.2/3.3 benchmarks from a new Intel Core i7 4770K "Haswell" system, but for those curious about the AMD side, here's some benchmarks.
Compiler benchmarks were done from Ubuntu 13.04 with LLVM Clang 3.1, LLVM Clang 3.3, and LLVM Clang 3.4 (from Friday) being built from source without assertions and in an optimized mode, for producing release-ready binaries. LLVM Clang 3.2 had to be skipped from this testing since when invoking LLVM/Clang 3.2, for whatever reason, it ended up crashing the system in its current hardware/software configuration.
The benchmarks in full for this round of compiler testing can be found on OpenBenchmarking.org via 1306228-PTS-LLVMAMDF95. Click that link for all of the system hardware/software details and the complete test results.
There have been some performance improvements from the AMD FX-8150 "Bulldozer" system when comparing LLVM Clang 3.1 to LLVM Clang 3.3, while overall there isn't too much exciting yet in the way of LLVM Clang 3.4, which won't be out until the end of the year or perhaps early next year. Coming up next will be some comparative benchmarks for this system against GCC and Open64.