What would be required to make a LLVM backend for GHC

Hi all, I've been talking to one of the LLVM developers, who's working on an operating system called AuroraUX, which, among other things, is trying to use LLVM as much as possible in the system (using clang as the default compiler, compiler-rt [libgcc replacement from the LLVM team], etc.). He would like to know exactly what would need to be implemented in LLVM to allow ghc to be ported to LLVM, and he would do his best to get these features implemented. I know the LLVM guys are quite open to suggestions, and want to get people using it as much as possible, so if we can let them know what we need, hopefully they can help make life easier for us. Thanks, Alex Mason