You could, for example, write a compiler in Python that generated native code (or LLVM bitcode to be passed to llc or whatever) via the LLVM API. Writing a compiler in Python vs. C/C++ would be a lot easier in a number of ways.

I'm not aware of any "production grade" compilers that do this, but no hard reason why not, I guess. Seems like it'd be nice for prototyping etc. if nothing else.

Want to make an obscure (your own?) language faster or extend it for your usecase? Write a frontend in python and let llvm do the hard parts.

Two big use cases are building your own compiler in Python and doing some JIT compilation (E.g. regex matcher or similar) to gain some perf.

LLVM is fantastic but not everyone wants or can use C++ in their project.

I've been doing prototype compilers in Haskell, but Python might also be a nice choice.