diff --git a/.travis.yml b/.travis.yml
index 58980f41..560fbb3d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,4 @@
+bundler_args: --without doc:util:site:benchmark:development
 language: ruby
 cache: bundler
 sudo: false
diff --git a/Gemfile b/Gemfile
index b253e8bf..c694a089 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,58 +1,62 @@
-source 'https://rubygems.org'
-gemspec name: 'jekyll'
+source "https://rubygems.org"
+gemspec :name => :jekyll
 
-gem 'rake', '~> 10.1'
+gem "rake", "~> 10.1"
 group :development do
-  gem 'rdoc', '~> 4.2'
-  gem 'launchy', '~> 2.3'
-  gem 'toml', '~> 0.1.0'
-  gem "rubocop"
-  gem 'pry'
+  unless ENV["CI"]
+    gem "pry", :require => false
+    gem "rubocop", {
+      :github => "bbatsov/rubocop",
+      :branch => :master, :require => false
+    }
+  end
+end
+
+group( :doc) { gem "rdoc", "~> 4.2" } # `--without doc`
+group(:util) { gem "launchy", "~> 2.3" } # `--without util`
+group(:site) { gem "html-proofer" } # `--without site`
+
+# `--without benchmark`
+group :benchmark do
+  gem "rbtrace"
+  gem "ruby-prof"
+  gem "benchmark-ips"
+  gem "stackprof"
 end
 
 group :test do
-  gem 'redgreen', '~> 1.2'
-  gem 'shoulda', '~> 3.5'
-  gem 'cucumber', '~> 2.1'
-  gem 'simplecov', '~> 0.9'
-  gem 'jekyll_test_plugin'
-  gem 'jekyll_test_plugin_malicious'
-  gem 'minitest-reporters'
-  gem 'minitest-profile'
-  gem 'rspec-mocks'
-  gem 'minitest'
-  gem 'nokogiri'
+  gem "redgreen", "~> 1.2"
+  gem "shoulda", "~> 3.5"
+  gem "cucumber", "~> 2.1"
+  gem "simplecov", "~> 0.9"
+  gem "jekyll_test_plugin"
+  gem "jekyll_test_plugin_malicious"
+  gem "minitest-reporters"
+  gem "minitest-profile"
+  gem "rspec-mocks"
+  gem "minitest"
+  gem "nokogiri"
 
   if RUBY_PLATFORM =~ /cygwin/ || RUBY_VERSION.start_with?("2.2")
-    gem 'test-unit'
-  end
-
-  if ENV['PROOF']
-    gem 'html-proofer', '~> 2.0'
+    gem "test-unit"
   end
 end
 
-group :benchmark do
-  if ENV['BENCHMARK']
-    gem 'ruby-prof'
-    gem 'rbtrace'
-    gem 'stackprof'
-    gem 'benchmark-ips'
+group :optional_jekyll_dependencies do
+  gem "toml", "~> 0.1.0"
+  gem "jekyll-paginate", "~> 1.0"
+  gem "jekyll-coffeescript", "~> 1.0"
+  gem "jekyll-feed", "~> 0.1.3"
+  gem "jekyll-redirect-from", "~> 0.9.1"
+  gem "jekyll-gist", "~> 1.0"
+  gem "mime-types", "~> 3.0"
+  gem "kramdown", "~> 1.9"
+
+  platform :ruby, :mswin, :mingw do
+    gem "rdiscount", "~> 2.0"
+    gem "pygments.rb", "~> 0.6.0"
+    gem "redcarpet", "~> 3.2", ">= 3.2.3"
+    gem "classifier-reborn", "~> 2.0"
+    gem "liquid-c", "~> 3.0"
   end
 end
-
-gem 'jekyll-paginate', '~> 1.0'
-gem 'jekyll-coffeescript', '~> 1.0'
-gem 'jekyll-feed', '~> 0.1.3'
-gem 'jekyll-redirect-from', '~> 0.9.1'
-gem 'jekyll-gist', '~> 1.0'
-gem 'mime-types', '~> 3.0'
-gem 'kramdown', '~> 1.9'
-
-platform :ruby, :mswin, :mingw do
-  gem 'rdiscount', '~> 2.0'
-  gem 'pygments.rb', '~> 0.6.0'
-  gem 'redcarpet', '~> 3.2', '>= 3.2.3'
-  gem 'classifier-reborn', '~> 2.0'
-  gem 'liquid-c', '~> 3.0'
-end