grinn, I'm still hopeful clang-format-indent-mode will eventually be accepted into the LLVM project, but for now you can try it out as a separate package:
https://gitlab.com/grinn.amy/clang-format-indent
If you are using clang-format in any of your projects, this might be useful to apply complex .clang-format rules as you type rather than after-the-fact.
Here's the pull request: