Tyler Allgeier rushed for 111 yards and scored two touchdowns, and No. 13-ranked BYU made a fourth-down stop at its own 10-yard line with 38 seconds remaining to hold off USC, 35-31, Saturday in Los Angeles.The Cougars (10-2) built a 28-13 early in the second half of their regular-season finale. Allgeier posted 9- and 5-yard touchdown runs in the second quarter, and Jaron Hall threw the second of his two touchdown passes early in the third quarter to put BYU ahead by the 15 points.Hall’s arcing, 41-yard pass to Keanu Hill threaded through two USC defenders. Hall found Puka Nacua on a 28-yard pass play in the first quarter.Having dropped four home games by double-digit margins this season, including a 62-33 defeat last week to rival UCLA, the Trojans (4-7) appeared headed for another lopsided home loss after the Hall-to-Hill touchdown.But the Trojans rallied for 18 consecutive points in the third and fourth quarters. Vavae Malepeai, who rushed for 99 yards, started the rally with a 2-yard scoring run midway through the third. Parker Lewis tacked on the third of his three field goals — a 37-yarder — before Jaxson Dart capped a 12-play, 91-yard drive with a 10-yard touchdown pass to Gary Bryant Jr. four minutes into the fourth quarter.The score put the Trojans up 31-28, their first lead since going up 3-0 on the game’s opening drive.Calen Bullock intercepted Hall on a deep pass into the end zone to end BYU’s subsequent possession, but the Trojans then went three-and-out and punted the ball back to BYU for what would become the game-winning drive.