Cheddi Mosely had 23 points to lead BU (7-10, 3-3), which shot 48.1 percent but went 22 of 41 on free throws.
Loyola rallied from a seven-point deficit in regulation, as Brito made a 3 with less than a second left. A flagrant foul on BU led to two free throws from Rassman to tie it. A foul on the inbounds pass gave BU's Eric Fanning two free throws, which he missed.
After two free throws from Mosely in overtime, Brito hit his go-ahead 3-pointer and Walker sealed it with four late free throws.