I don\'t manage to install therubyracer gem on Yosemite 10.10.
Here is the log:
11:53 $ gem install libv8 -v \'3.16.14.3\' -- --with-system-v8 Building
git clone https://github.com/cowboyd/libv8.git
cd libv8
bundle install
bundle exec rake clean build binary
gem install pkg/libv8-3.16.14.3-x86_64-darwin-12.gem #note that libv8 version may change, so tab through files in pkg/, also remember to use the one with version specified
then just bundle your project gems
this is the only way it worked for me on 10.10 (ruby 2.1.2)