Is there a way to see more verbose output from Clang?

Question

I would like to see a more detailed output from clang , more than it appears at startup as clang -v .

So far I tried: clang --help , clang --help-hidden and clang -cc1 --help , but did not find anything that could help.

I am particularly interested in whether I can see traces of reasoning that clang makes to decide whether to recompile a specific .cpp file.