Los Angeles improved its fading playoff hopes, having started the day 4 1/2 games behind St. Louis for the second wild card position in the National League.
Adrian Gonzalez drove in two of the Dodgers' first three runs with singles in the first and third innings. Kemp then delivered a two-run double in the fourth and hit his two-run home run in the sixth to give Los Angeles an 8-0 lead.
The beneficiary of Los Angeles' 14-hit attack was Aaron Harang (10-10), who ended a five-start winless streak by throwing 5 1/3 shutout innings. He allowed four hits and four walks.
Clayton Richard (14-13) surrendered four earned runs on 10 hits over 3 2/3 to take the loss.
Los Angeles won 30 of its first 44 games this season, but has gone 50-62 since then and fallen close to playoff elimination.