The 15th-ranked Cowboys produced the most dramatic finish of the day after co-champions Kansas and Kansas State rolled to one-sided victories.
No. 6 Kansas reached the semifinals with a 91-63 blasting of Texas Tech, 12th-ranked Kansas State was a 66-49 winner over Texas and Iowa State defeated Oklahoma 73-66.
Kansas and Iowa State will meet in Friday's first semifinal, followed by Oklahoma State against Kansas State.
Baylor staged a tremendous comeback after trailing by 18 points at halftime and tied the game on a 4-point play with 19 seconds remaining
Forte, however, finished off a 6-of-6 effort from the foul line and wound up with 14 points. Marcus Smart scored 21 points for the Cowboys, who defeated Kansas State last Saturday to end the regular season.
Melvin Ejim scored 23 points and seized 12 rebounds in leading Iowa State (22-10), which came back from a double-digit deficit to win its third in a row.
Oklahoma led by as many as 14 in the first half, but Iowa State took the lead for good at 66-63 on a 3-pointer by Tyus McGee.
Kansas moved closer to its ninth Big 12 tournament crown, getting 24 points from Ben McLemore. The Jayhawks (27-5) defeated Iowa State in their two regular-season meetings, but had to go to overtime in both games to do it.
Kansas finished the first half on a 7-0 run and put together a 10-0 spurt early in the second half against the red Raiders.
Kansas State pulled away late against Texas with Rodney McGruder scoring 24 points. He was 4-of-8 from 3-point range.