I've been doing make -j70 and -j70 restrap and libasan seems to build 1 file at a time. I'm chasing other bits right now, so I didn't track down what did it. I looked at how it is wired up and didn't just spot it, and it seems to copy other runtime libraries we have. Not sure if they suffer the same problem or not. It was amazing how slowly it was building, which was noticeably slower than the rest of the build.
Any hints on where to look? I can run experiments if someone wants to take a guess.
