Recommended cpu emulator for OS X

Is there a recommended cpu emulator that I can use as a backend?

I just finish porting the libcpu project to llvm tot (3.0) enough so that it builds
without warnings, however I'm not sure if the result works (on OS X 10.7.1).
Seems like the fibonacci test only works for m88k, the others seem to continually
dump the module. Regardless since the project does not seem too active, I don't
want to bother going forward in my debugging effort; especially if project no longer
being used. Is libcpu recommended as a backend emulator? My purposes are
pedagogical in that I want to start learning LLVM backend infrastructure with a
simpler instruction set than x86/x86-64 (arm would be nice also).

Thanks in advance