Clang and GCC have a feature (-MD flag) to create a dependency file
in a format that make command can read, so that you don't have to
manually maintain dependencies between .c files and .h files.
There was no corresponding feature in the linker. With this patch, you
can now do the same thing by passing --dependency-files=<path> to lld.
I believe this option is worth adding.
This is an example of a generated file:
https://gist.github.com/rui314/f5e2c669c70bec31f260bfd4b8ef41a6
This probably should be
Some StringRef elements are not internalized.