How to add "Other Linker Flags" to xcode project using command line?

@Jesse Rusak's answer works, but it is a bit simpler to directly add options to the command line, being careful to escape variables from your shell like

xcodebuild ... "OTHER_LDFLAGS=\$(OTHER_LDFLAGS) -all_load"

You can do this by specifying an xcconfig file to xcodebuild. For example:

echo 'OTHER_LDFLAGS = $(OTHER_LDFLAGS) -force_load "$(SRCROOT)/calabash.framework/calabash" -lstdc++' > temp.xcconfig
xcodebuild -xcconfig temp.xcconfig ...