For dmd you use build.d that is in the repository.
For phobos win64.mak (used for 32bit by default as well):
"# Makefile to build D runtime library phobos{64,32mscoff}.lib for
Windows MSVC"
So MSVC make.
Beyond that idk, but its starting point (oh and druntime is now in dmd
repo, so ugh... yeah)