You could take a look at Sulong (1) for this. Sulong is an LLVM BC interpreter that also supports both IR-level and source-level debugging. The IR-level debugging feature described at (2) sounds very much like what James wants to have. Sulong is part of GraalVM (3) which provides builds for multiple platforms.
I apologize for not replying to the specific thread. I am working on Sulong rather than LLVM, so I only receive this mailing list as a digest to keep up with the latest developments of this project and usually don't participate in any discussions here.