I'm happy to announce that LLVM has a new compiler-rt subproject. This project implements low-level compiler library functions provided by "libgcc". It also includes the Apple "Blocks" runtime library, but it is not currently well integrated into the build system. If you are interested in finding out more, we have a simple web page available here: http://compiler-rt.llvm.org/
The code in this project is far enough along to support various darwin platforms, but we'd really like to see others contribute to it to increase its portability and breadth of coverage. Many of the routines included are already significantly higher performance than the ones in libgcc, and the framework is there to add new routines for other targets.
Many people contributed code to this, including:
Thanks for their hard work!