The 2015 Sprint Cup champion beat Kevin Harvick by 0.415 seconds in the race that went 61 laps instead of the 60 scheduled. Paul Menard was third, 1.338 seconds back.
It was Busch's seventh victory of the season and record-extending 83rd of his career and came on a weekend where he has dominated the 2.5-mile oval on both the Xfinity and Cup circuits.
He posted the fastest practice times in both series Friday, won both poles Saturday and can sweep both races for the second straight year by winning the Brickyard 400 on Sunday.
Busch surrendered the lead once when he pitted and held off Harvick, who took new tires during a late caution that led to the overtime.
