Since LLVM 14 has stopped changing and is about to be released,
back-patch the following changes from the master branch:
e6a7600202105919bffd62b3dfd941f4a94e082b
807fee1a39de6bb8184082012e643951abb9ad1d
a56e7b66010f330782243de9e25ac2a6596be0e1
Back-patch to 11, where LLVM JIT support came in.