Impossible
The B2 has insufficient propulsion to fly very fast. It can't even go supersonic - more like a commercial airliner. High thrust engines with afterburners are not consistent with stealth. You may be thinking of the B1, which is semi-stealthy and can fly very fast, but is more of a light attack bomber like the old B58 Hustler or earlier B47 Stratojet.
The B2 has one advantage not forseen when it was being designed - it can carry a lot of smart weapons, like a bloated F117. But that is not its designed mission, and against a capable opponent it would fail miserably in that role.
