therubyracer - Gem::Ext::BuildError: ERROR: Failed to build gem native extension

This steps worked for me.

OS: Maverick Ruby: 2.1.1

gem uninstall libv8
gem install therubyracer -v '0.11.3'
gem install libv8 -v '3.11.8.13' -- --with-system-v8

For those facing this problem in OS X El Capitan, this solution from a therubyracer issue thread was what finally worked for me:

brew tap homebrew/versions
brew install v8-315

gem install libv8 -v '3.16.14.13' -- --with-system-v8
gem install therubyracer -- --with-v8-dir=/usr/local/opt/v8-315

bundle install

I had also run brew install gcc prior, but I'm not sure whether this was in fact necessary.

Try first uninstalling libv8 gem, then install rubyracer, and then libv8

gem uninstall libv8
gem install therubyracer
gem install libv8 -- --with-system-v8