Yea, you can also see from the linked dashboards that it's writing way more stuff at the end of the build. I was watching the log just now and it looks like it's linking some things. I hope someone with more Bazel and LLVM knowledge can give this a go. I just wanted to toss something up as a "what would it be like if I just compiled this project" perspective.

This is absolutely not a definitive "X is better than Y" since X and Y are completely different things.