xcode-select --install sudo easy_install pip sudo CPATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/libxml2 CFLAGS=-Qunused-arguments CPPFLAGS=-Qunused-arguments pip install lxml
URL:http://stackoverflow.com/questions/19548011/cannot-install-lxml-on-mac-os-x-10-9