I'm not sure about moral per se, but LLVM is practically a painful dependency—it doesn't have API compatibility between versions, release builds are rapidly approaching a gigabyte, you are given some franken-version by the system, and you won't have a good time if you end up linking/loading more than one version for whatever reason.
IIRC there was also some case where an LLVM bump caused tcmalloc to explode inside wine.
IIRC there was also some case where an LLVM bump caused tcmalloc to explode inside wine.