Will create a temporary git and add the entire module LLVM-IR and
commit it, after each passes.
For reference, this was discussed on llvm-dev here: http://lists.llvm.org/pipermail/llvm-dev/2018-March/121634.html
My personal view is that it would make more sense to dump the raw information you're after in a trivially machine readable way (a minor modification to -print-after-all?), and use an external script to post-process that output (e.g. committing to git). It might make sense to commit such a script to the utils/ subdir. That would be more general purpose, and avoid the concern of what to do when someone wants to come along and add a HgCommitModule or similar.
It was pointed out that upstream support for dumping the whole module already exists. It's spelled as: -print-after-all -print-module-scope
Given this, you should be able to do this by post processing a log without needing any LLVM changes.