The router that connects llvm.org to the CS network (and hence, the world) went belly-up about 20 minutes ago. Our department IT people just put in a new interim switch, so connectivity should be restored.
I imagine that, at some point, they may put in a new, permanent switch. There will be some minor network interruption for that, but switching over to a new router is so quick that I doubt we'll notice if/when they do that.
Sorry for the trouble.
-- John T.