This started somewhere before rev.122456, resulting libLLVM-2.9svn.dylib is unusabkle since it has double 'lib' embedded in its path.
otool -l /opt/local/llvm/svn-r122842/lib/libLLVM-2.9svn.dylib
produces this line (among others):
name /opt/local/llvm/svn-r122842/lib/lib/libLLVM-2.9svn.dylib (offset 24)
The way how things are on Apple, all apps read this path during link phase, look for it during dynamic linking and fail.
Yuri