Marcum (3-3) struck out nine while allowing six hits and walking two, breaking a personal two-game losing streak. The right-hander threw 80 of his 119 pitches for strikes as the Brewers began a four-game set at Dodger Stadium with a victory, snapping a two-game skid.
The Brewers broke a 1-1 tie in the sixth with a pair of unearned runs after Norichika Aoki reached on pitcher Aaron Harang's throwing error. Aramis Ramirez drove him in with a single and Rickie Weeks added a sacrifice fly in the rally.
Harang (3-3) absorbed the loss, yielding three runs on four hits over five innings for the National League West-leading Dodgers.