[LLVMdev] setting up LLVM to *run on* amd64 but *generate code* for alpha

[Bob Wilson]

The bigger picture here is that you don't need to do anything special  
to build LLVM as a cross compiler.  If you just run configure for LLVM  
without any --target options, the default is to include all the  
backends.  You can then select a particular backend at runtime.

It is only when you build llvm-gcc, which I understand you aren't  
interested in right now, that you need to specify --target to configure.