My guess? He flies backwards around the world until his beard shrinks back into his face.
It might not have occurred to you while watching the Man of Steel trailer that since Clark Kent is depicted as having a beard in one shot, at some point he had to learn how to shave -- which would probably be incredibly difficult considering the strength of his hair follicles. Razor company Gillette has definitely picked up on this, of course. They've launched a tie-in marketing campaign to postulate about how the Last Son of Krypton manages to look so clean-shaven all the time, and they've enlisted the help of Bill Nye, Mayim Bialik, Kevin Smith,and the Mythbusters to do it.