With St. Louis trailing 1-0 in the sixth, John Jay singled and Allen Craig (3-for-5, two runs scored) doubled with none out off Cliff Lee (2-7) and Holliday followed by smacking a pitch into the first row of the right field seats.
Holliday went 3-for-5 and reached base for his 34th consecutive game.
Westbrook (12-8) held the Phillies to one run on four hits over 7 2/3 innings, walking two and striking out three.
Jason Motte picked up his 26th save for St. Louis, which evened its three-game series.
Lee finished by allowing four runs on 10 hits in a seven-inning stint.
Ryan Howard drove in the Phillies' only run.