Pence, who has 17 homers and 15 doubles this season, will likely start in right field for the Giants, who are tied with the Dodgers for first in the division, 3 1/2 games ahead of Arizona.
Pence, 29, is eligible for arbitration in the off-season after making around $10 million this season. He has clubbed 131 homers and 172 doubles over 835 career games -- 680 of them with Houston.
Schierholtz, who has spent his entire six-year career with the Giants, has a .257 batting average with five homers in 77 games this year. The outfielder sports a .270 average with 23 homers in 503 career games.
Also going to Philadelphia were catching prospect Tommy Joseph, minor league pitcher Seth Rosin and cash.