Xcode 5.1 get clang: error: unknown argument: '-mno-fused-madd'

Building Pillow for Python in virtualenvwrapper. I am told that "unknown argument" is now treated as a hard error in Xcode 5.1. Any way to work around this without modifying build flags in Pillow? I installed this package successfully before but can't remember how. Can you compile C code in Mavericks OS without installing Xcode? I may have been using Xcode 5.0 before and upgraded to 5.1. Any easy way to downgrade back?