diff --git a/lib/bundler.rb b/lib/bundler.rb
index 68d5dc3368a..d695708d2b2 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -33,6 +33,7 @@ module Bundler
   autoload :Fetcher,                "bundler/fetcher"
   autoload :FeatureFlag,            "bundler/feature_flag"
   autoload :GemHelper,              "bundler/gem_helper"
+  autoload :Gemfile,                "bundler/gemfile"
   autoload :GemHelpers,             "bundler/gem_helpers"
   autoload :GemRemoteFetcher,       "bundler/gem_remote_fetcher"
   autoload :GemVersionPromoter,     "bundler/gem_version_promoter"
diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index f1ff3f45543..f386e685178 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -355,6 +355,16 @@ def add(*gems)
       Add.new(options.dup, gems).run
     end
 
+    desc "canonical [OPTIONS]", "Prettifies the Gemfile"
+    long_desc <<-D
+      Prettifies the Gemfile by giving it consistent ordering and formatting.
+    D
+    method_option "view", :type => :boolean
+    def canonical
+      require "bundler/cli/canonical"
+      Canonical.new(options).run
+    end
+
     desc "outdated GEM [OPTIONS]", "List installed gems with newer versions available"
     long_desc <<-D
       Outdated lists the names and versions of gems that have a newer version available
diff --git a/lib/bundler/cli/canonical.rb b/lib/bundler/cli/canonical.rb
new file mode 100644
index 00000000000..e0bb9e904bd
--- /dev/null
+++ b/lib/bundler/cli/canonical.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Canonical
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      contents = Gemfile.full_gemfile(:show_summary => true, :as_string => true)
+
+      if @options[:view]
+        puts contents
+      else
+        SharedHelpers.write_to_gemfile(Bundler.default_gemfile, contents)
+      end
+    end
+  end
+end
diff --git a/lib/bundler/gemfile.rb b/lib/bundler/gemfile.rb
new file mode 100644
index 00000000000..a977e9a4700
--- /dev/null
+++ b/lib/bundler/gemfile.rb
@@ -0,0 +1,110 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Gemfile
+    def self.full_gemfile(options = {})
+      gemfile = new(options)
+      gemfile.full_gemfile
+    end
+
+    def initialize(options = {})
+      @options = options
+      @resolve = nil
+    end
+
+    def full_gemfile
+      definition = Bundler.definition
+      @resolve = definition.resolve if @options[:show_summary]
+
+      gemfile = []
+      Array(definition.send(:sources).global_rubygems_source).each do |s|
+        s.remotes.each {|r| gemfile << "source #{r.to_s.dump}" }
+      end
+
+      gemfile << nil
+
+      definition.dependencies.group_by(&:groups).each_key(&:sort!).sort_by(&:first).each do |groups, deps|
+        gemfile << groups_wise(deps, groups)
+      end
+
+      if @options[:as_string]
+        gemfile.join("\n").gsub(/\n{3,}/, "\n\n").strip
+      else
+        gemfile
+      end
+    end
+
+    # @param  [Bundler::Dependency] dep         Dependency instance of the gem
+    # @param  [Boolean]             show_groups Whether groups be shown in gem contents
+    # @return [[String]]
+    def gem_contents(dep, show_groups = false)
+      contents = []
+      contents << "gem " << dep.name.dump
+
+      contents << ", " << dep.requirement.as_list.map(&:inspect).join(", ") unless dep.requirement.none?
+
+      if show_groups || @options[:inline_groups]
+        groups = dep.groups.reject {|g| g.to_s == "default" }.uniq
+
+        unless groups.empty?
+          contents << if groups.size == 1
+                        ", :group => :#{groups[0]}"
+                      else
+                        ", :groups => #{groups.inspect}"
+                      end
+        end
+      end
+
+      contents << ", :source => \"" << dep.source.remotes << "\"" unless dep.source.nil?
+      # contents = ["gemspec"] if @dep.source.options["gemspec"]
+
+      contents << ", :platforms => " << dep.platforms.inspect unless dep.platforms.empty?
+
+      env = dep.instance_variable_get(:@env)
+      contents << ", :env => " << env.inspect if env
+
+      if (req = dep.autorequire) && !req.empty?
+        req = req.first if req.size == 1
+        contents << ", :require => " << req.inspect
+      end
+
+      contents
+    end
+
+    def groups_wise(deps, groups)
+      gemfile = []
+      groups = nil if groups.empty? || groups.include?(:default)
+
+      group_block = groups && !@options[:inline_groups]
+      inside_group = !groups.nil? && !@options[:inline_groups]
+      gemfile << "group #{groups.map(&:inspect).uniq.join(", ")} do" if group_block
+      gemfile << deps_contents(deps.sort_by(&:name), inside_group)
+      gemfile << "end" if group_block
+      gemfile << nil
+
+      gemfile
+    end
+
+  private
+
+    # @param [[Bundler::Dependency]] deps         Array of dependency instances of gems
+    # @param [Boolean]               inside_group Whether gems to be shown are inside group
+    # @return [[String]]
+    def deps_contents(deps, inside_group = false)
+      contents = []
+      deps.each do |dep|
+        if @options[:show_summary]
+          spec = @resolve[dep.name].first.__materialize__
+          contents << "#{"  " if inside_group}# #{spec.summary}"
+        end
+
+        gem = []
+        gem << "  " if inside_group
+        gem << gem_contents(dep)
+        contents << gem.join
+      end
+
+      contents
+    end
+  end
+end
diff --git a/man/bundle-canonical.ronn b/man/bundle-canonical.ronn
new file mode 100644
index 00000000000..d4bfc780bba
--- /dev/null
+++ b/man/bundle-canonical.ronn
@@ -0,0 +1,17 @@
+bundle-canonical(1) -- Prettifies the Gemfile
+===========================================================================
+
+## SYNOPSIS
+
+`bundle canonical` [--view]
+
+## DESCRIPTION
+
+Prettifies the Gemfile by giving it consistent ordering and formatting.
+
+If not, the first missing gem is listed and Bundler exits status 1.
+
+## OPTIONS
+
+* `--view`:
+  Displays what the Gemfile would look like on change but does not change the Gemfile.
diff --git a/spec/bundler/gemfile_spec.rb b/spec/bundler/gemfile_spec.rb
new file mode 100644
index 00000000000..c78ca641d53
--- /dev/null
+++ b/spec/bundler/gemfile_spec.rb
@@ -0,0 +1,112 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Gemfile do
+  before :each do
+    install_gemfile <<-G
+      source "file://#{gem_repo1}"
+      gem "weakling", "~> 0.0.1"
+      gem "rack-test", :group => :test
+      gem "rack", :groups => [:prod, :dev]
+      gem "rspec", :group => :test
+    G
+  end
+
+  context "#gem_contents" do
+    it "with show_groups true" do
+      definition = Bundler.definition
+      contents = subject.gem_contents(definition.dependencies.find {|d| d.name == "rack" }, true)
+      contents2 = subject.gem_contents(definition.dependencies.find {|d| d.name == "rack-test" }, true)
+      expect(contents.join).to eq("gem \"rack\", :groups => [:prod, :dev]")
+      expect(contents2.join).to eq("gem \"rack-test\", :group => :test")
+    end
+
+    it "with show_groups false" do
+      definition = Bundler.definition
+      contents = subject.gem_contents(definition.dependencies.find {|d| d.name == "rack" }, false)
+      expect(contents.join).to eq("gem \"rack\"")
+    end
+  end
+
+  context "#groups_wise" do
+    it "returns group wise gems" do
+      definition = Bundler.definition
+      a = definition.dependencies.group_by(&:groups).each_key(&:sort!).sort_by(&:first)
+      expected = <<-E
+      group :test do
+        gem "rack-test"
+        gem "rspec"
+      end
+      E
+
+      deps = a[2][1]
+      groups = a[2][0]
+      expect(subject.groups_wise(deps, groups).join("\n").gsub(/\n{3,}/, "\n\n")).to eq(strip_whitespace(expected))
+    end
+  end
+
+  describe "#full_gemfile" do
+    context "without show_summary" do
+      subject { Bundler::Gemfile.new(:as_string => true) }
+
+      it "does not show summary" do
+        expected = <<-E
+        source "file://#{gem_repo1}"
+
+        gem "weakling", "~> 0.0.1"
+
+        group :dev, :prod do
+          gem "rack"
+        end
+
+        group :test do
+          gem "rack-test"
+          gem "rspec"
+        end
+        E
+        expect(subject.full_gemfile).to eq(strip_whitespace(expected))
+      end
+    end
+
+    context "with show_summary" do
+      subject { Bundler::Gemfile.new(:as_string => true, :show_summary => true) }
+      it "shows summary" do
+        expected = <<-E
+        source "file://#{gem_repo1}"
+
+        # This is just a fake gem for testing
+        gem "weakling", "~> 0.0.1"
+
+        group :dev, :prod do
+          # This is just a fake gem for testing
+          gem "rack"
+        end
+
+        group :test do
+          # This is just a fake gem for testing
+          gem "rack-test"
+          # This is just a fake gem for testing
+          gem "rspec"
+        end
+        E
+        expect(subject.full_gemfile).to eq(strip_whitespace(expected))
+      end
+    end
+
+    context "with inline_groups" do
+      subject { Bundler::Gemfile.new(:as_string => true, :inline_groups => true) }
+      it "shows summary" do
+        expected = <<-E
+        source "file://#{gem_repo1}"
+
+        gem "weakling", "~> 0.0.1"
+
+        gem "rack", :groups => [:dev, :prod]
+
+        gem "rack-test", :group => :test
+        gem "rspec", :group => :test
+        E
+        expect(subject.full_gemfile).to eq(strip_whitespace(expected))
+      end
+    end
+  end
+end
diff --git a/spec/commands/canonical_spec.rb b/spec/commands/canonical_spec.rb
new file mode 100644
index 00000000000..911f13ef223
--- /dev/null
+++ b/spec/commands/canonical_spec.rb
@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+RSpec.describe "bundle canonical" do
+  before :each do
+    install_gemfile <<-G
+      source "file://#{gem_repo1}"
+      gem "weakling", "~> 0.0.1"
+      gem "rack-test", :group => :test
+      gem "rack", :groups => [:prod, :test]
+    G
+  end
+
+  context "with --view option" do
+    it "does not update gemfile but displays expected gemfile" do
+      bundle! "canonical --view"
+      output = <<-G
+       source "file://#{gem_repo1}"
+
+       # This is just a fake gem for testing
+       gem "weakling", "~> 0.0.1"
+
+       group :prod, :test do
+         # This is just a fake gem for testing
+         gem "rack"
+       end
+
+       group :test do
+         # This is just a fake gem for testing
+         gem "rack-test"
+       end
+      G
+
+      expect(out).to eq(strip_whitespace(output))
+      gemfile_should_be <<-G
+        source "file://#{gem_repo1}"
+        gem "weakling", "~> 0.0.1"
+        gem "rack-test", :group => :test
+        gem "rack", :groups => [:prod, :test]
+      G
+    end
+  end
+
+  context "without --view option" do
+    it "updates gemfile" do
+      bundle! "canonical"
+
+      gemfile_should_be <<-G
+       source "file://#{gem_repo1}"
+
+       # This is just a fake gem for testing
+       gem "weakling", "~> 0.0.1"
+
+       group :prod, :test do
+         # This is just a fake gem for testing
+         gem "rack"
+       end
+
+       group :test do
+         # This is just a fake gem for testing
+         gem "rack-test"
+       end
+      G
+    end
+  end
+end