McCoy is 42-7 in his career, tying the wins record set by former Georgia quarterback David Greene.
Texas led 40-0 by halftime with McCoy throwing touchdown passes of 3 and 7 yards to Jordan Shipley. Cody Johnson ran for 109 yards and two short touchdowns and Tre' Newton added a 45-yard scoring run.
Texas (10-0, 6-0 Big 12) reached 10 wins for the ninth straight season, second only to Florida State's run of 14 consecutive 10-win seasons from 1987-2000.
Baylor (4-6, 1-5) dropped its fifth loss in six games.