Upton hit his seventh home run of the season. Chris Johnson had four hits and two RBIs for the Braves, who took a 7-0 lead in the third inning against Gio Gonzalez (1-1).
In sweeping their NL East rivals and compiling the best record in the major leagues, Atlanta (11-1) has outscored the opposition 62-23 and built a 20-6 advantage in home runs.
The Braves have swept three straight series (Cubs, Miami and Washington) for the first time since April 2000, when they swept four in a row (Phillies, Pirates, Dodgers, and Padres).
Maholm (3-0) pitched two-hit ball into the eighth inning.