It was the most rushing yards Texas has given up in school history, too, surpassing the 452 it yielded to Rice in 1997.
BYU quarterback Taysom Hill ran for 259 yards, the second-most ever by a Cougar QB (Eldon Fortie once had 272), and gashed the Longhorns time and again with long runs, including a 68-yarder in the first half. Hill finished with three rushing touchdowns, and recorded the second-best rushing performance ever at BYU.
That offset the sophomore's miserable passing performance. He was 9 for 26 for 129 yards and an interception as the Cougars struggled again in the throwing game after losing 19-16 to Virginia last week due partly to horrendous offensive line play.
Against Texas, however, a shuffled offensive line was dominant, and the Cougars stopped passing, for the most part, when they realized they could steamroll the visitors.
Jamaal Williams also got into the act, rushing for a career-high 182 yards on 30 carries. Paul Lasike picked up 87 on 15 attempts.
The Cougars ran 59 plays in the first half and racked up 411 yards alone in the first 30 minutes, 349 of it on the ground. They finished with 99 plays.
Hill was the catalyst in the ground attack in the first half, rushing 12 times for 166 yards and two touchdowns to give the Cougars a 27-14 lead at the break.
His tackle-breaking 68-yard jaunt late in the first quarter gave the Cougars a 10-7 lead and was the longest run by a quarterback in school history.
After Duke Thomas intercepted a poorly thrown ball by Hill, the Longhorns regained the lead, 14-10, with a nine-play 76-yard drive.
Texas appeared to have stopped BYU's next drive, but a running into the kicker penalty gave the Cougars life, and Hill again found the end zone on a long run. The Longhorns never recovered.
His 20-yard scamper lifted BYU to a 17-14 lead with 7:48 remaining in the first half.
The Cougars stayed with the ground attack after a Texas punt, and went 59 yards on nine plays all but one of them a running play to move ahead 24-14.
Just before halftime, another long BYU drive, 75 yards, ended with Justin Sorensen's 32-yard field goal.
Quarterback David Ash was 10 for 17 for 147 yards in the first half, and finished 19 of 34 for 251 yards and two touchdowns.
R In short • BYU rushes for a school-record 550 yards and upsets No. 15-ranked Texas at LaVell Edwards Stadium.
Key Moment • A roughing-the-kicker penalty on Texas prolongs a BYU drive, and the Cougars take a 17-14 lead they would not relinquish.