Starting with our first test, LAME MP3 encoding, the binary resulting from LLVM-GCC was slower than the GCC build. It took 82 seconds to encode the sample MP3 file using the GCC binary, but 92 seconds with the LLVM-GCC version.
The dcraw test profile was also slower with LLVM-GCC, but by a smaller margin compared to the MP3 encoding test. Using LLVM-GCC took a few seconds longer with this real-world task.
Striking a win for LLVM-GCC was the OpenSSL test profile. The binary from the LLVM front-end with GCC back-end resulted in about a 30% signs per second boost in OpenSSL, but still this performance was well below where Ubuntu 9.10 is running on the very same system.