Graphical 3 way merging for Git using P4Merge

.gitconfig

# Download and install P4Merge from here: http://www.perforce.com/product/components/perforce-visual-merge-and-diff-tools
# And then add this to your Git config

[merge]
        tool = p4mergetool
[mergetool "p4mergetool"]
        cmd = /Applications/p4merge.app/Contents/Resources/launchp4merge $PWD/$BASE $PWD/$REMOTE $PWD/$LOCAL $PWD/$MERGED
        trustExitCode = false
[diff]
        tool = p4mergetool
[difftool "p4mergetool"]
        cmd = /Applications/p4merge.app/Contents/Resources/launchp4merge $LOCAL $REMOTE