[lld] [llvm] [clang] Embed the command line arguments during LTO (PR #79390)

[Duncan Ogilvie via cfe-commits]

mrexodia wrote:

> I haven't checked closely yet, but it seems like you need to add tests.

Could you provide some guidance on what kind of tests to add and how to actually run them locally? First I wanted to get the builtkite job to be green, but it seems to be failing on some unrelated test where LLD cannot be found.

https://github.com/llvm/llvm-project/pull/79390