An error occurred while installing libv8 (3.11.8.13), and Bundler cannot continue

 I was getting that error on Mac 10.9.4. I had to update the gems :

gem 'libv8', '3.16.14.7'
gem 'therubyracer', '~> 0.12.0'

to fix this problem.

Reference : An error occurred while installing libv8 – Mavericks