Hamels has struck out 12 and walked two Saturday. He has thrown 112 pitches.
Center fielder Odubel Herrera made a long run to catch David Ross' one-out flyball in the eighth, tumbling on the warning track in front of the ivy on the wall after making the grab.
The Phillies lead 5-0.
Hamels has been the subject of trade talk with the July 31 dealing deadline less than a week away. The 31-year-old lefty was the MVP of the 2008 World Series.
Hamels combined with three relievers on a no-hitter at Atlanta last Sept. 1. He pitched six innings in that game, then left on a hot afternoon at Turner Field.
The Cubs have not been held hitless since Sandy Koufax pitched a perfect game against them in 1965.