diff --git a/.gitignore b/.gitignore
index e6f19f20..81330d87 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,10 @@
-tmp/
-modules/
 *.gem
-Gemfile.lock
 .bundle/
+.ruby-version
+.vscode/
+Gemfile.lock
+bin/bundle
+bin/rspec
+modules/
+tmp/
+vendor/
diff --git a/README.md b/README.md
index 8d7d2e00..13eee0e7 100644
--- a/README.md
+++ b/README.md
@@ -176,27 +176,29 @@ touching the modules, you can deactivate the hook.
 msync hook deactivate
 ```
 
-#### Submitting PRs to GitHub
+#### Submitting PRs/MRs to GitHub or GitLab
 
-You can have modulesync submit Pull Requests on GitHub automatically with the
-`--pr` CLI option.
+You can have modulesync submit Pull Requests on GitHub or Merge Requests on
+GitLab automatically with the `--pr` CLI option.
 
 ```
 msync update --pr
 ```
 
-You must set `GITHUB_TOKEN` in your environment for this to work. Other options
-include:
+You must set the `GITHUB_TOKEN` or `GITLAB_TOKEN` environment variable
+for GitHub PRs or GitLab MRs to work. Additional options:
 
-* Set the PR title with `--pr-title` or in `modulesync.yml` with the `pr_title`
-  attribute.
-* Assign labels to the PR with `--pr-labels` or in `modulesync.yml` with the
-  `pr_labels` attribute. **NOTE:** `pr_labels` should be a list. When using
-  the `--pr-labels` CLI option, you should use a comma separated list.
+* Set the PR/MR title with `--pr-title` or in `modulesync.yml` with the
+  `pr_title` attribute.
+* Assign labels to the PR/MR with `--pr-labels` or in `modulesync.yml` with
+  the `pr_labels` attribute. **NOTE:** `pr_labels` should be a list. When
+  using the `--pr-labels` CLI option, you should use a comma separated list.
 
-You can optionally set the `GITHUB_BASE_URL` environment variable to use GitHub
-Enterprise. This is passed to Octokit's [`api_endpoint`](https://github.com/octokit/octokit.rb#interacting-with-the-githubcom-apis-in-github-enterprise) 
-configuration option.
+For GitHub Enterprise and self-hosted GitLab instances you need to set the
+`GITHUB_BASE_URL` or `GITLAB_BASE_URL` environment variable in addition.
+More details for GitHub:
+
+* Octokit [`api_endpoint`](https://github.com/octokit/octokit.rb#interacting-with-the-githubcom-apis-in-github-enterprise)
 
 ### Using Forks and Non-master branches
 
@@ -258,8 +260,8 @@ Available parameters for modulesync.yml
 * `remote_branch` : Remote branch to push to (Default: Same value as branch)
 * `message` : Commit message to apply to updated modules.
 * `pre_commit_script` : A script to be run before commiting (e.g. 'contrib/myfooscript.sh')
-* `pr_title` : The title to use when submitting PRs to GitHub.
-* `pr_labels` : A list of labels to assign PRs created on GitHub.
+* `pr_title` : The title to use when submitting PRs/MRs to GitHub or GitLab.
+* `pr_labels` : A list of labels to assign PRs/MRs created on GitHub or GitLab.
 
 ##### Example
 
diff --git a/lib/modulesync.rb b/lib/modulesync.rb
index 33478266..e8e55dd4 100644
--- a/lib/modulesync.rb
+++ b/lib/modulesync.rb
@@ -1,5 +1,4 @@
 require 'fileutils'
-require 'octokit'
 require 'pathname'
 require 'modulesync/cli'
 require 'modulesync/constants'
@@ -10,12 +9,6 @@
 require 'modulesync/util'
 require 'monkey_patches'
 
-GITHUB_TOKEN = ENV.fetch('GITHUB_TOKEN', '')
-
-Octokit.configure do |c|
-  c.api_endpoint = ENV.fetch('GITHUB_BASE_URL', 'https://api.github.com')
-end
-
 module ModuleSync # rubocop:disable Metrics/ModuleLength
   include Constants
 
@@ -136,48 +129,22 @@ def self.manage_module(puppet_module, module_files, module_options, defaults, op
     if options[:noop]
       Git.update_noop(git_repo, options)
     elsif !options[:offline]
-      # Git.update() returns a boolean: true if files were pushed, false if not.
       pushed = Git.update(git_repo, files_to_manage, options)
-      return nil unless pushed && options[:pr]
-
-      manage_pr(namespace, module_name, options)
-    end
-  end
-
-  def self.manage_pr(namespace, module_name, options)
-    if options[:pr] && GITHUB_TOKEN.empty?
-      $stderr.puts 'Environment variable GITHUB_TOKEN must be set to use --pr!'
-      raise unless options[:skip_broken]
-    end
-
-    # We only do GitHub PR work if the GITHUB_TOKEN variable is set in the environment.
-    repo_path = File.join(namespace, module_name)
-    github = Octokit::Client.new(:access_token => GITHUB_TOKEN)
-
-    # Skip creating the PR if it exists already.
-    head = "#{namespace}:#{options[:branch]}"
-    pull_requests = github.pull_requests(repo_path, :state => 'open', :base => 'master', :head => head)
-    if pull_requests.empty?
-      pr = github.create_pull_request(repo_path, 'master', options[:branch], options[:pr_title], options[:message])
-      $stdout.puts "Submitted PR '#{options[:pr_title]}' to #{repo_path} - merges #{options[:branch]} into master"
-    else
-      $stdout.puts "Skipped! #{pull_requests.length} PRs found for branch #{options[:branch]}"
+      pushed && options[:pr] && @pr.manage(namespace, module_name, options)
     end
-
-    # PR labels can either be a list in the YAML file or they can pass in a comma
-    # separated list via the command line argument.
-    pr_labels = Util.parse_list(options[:pr_labels])
-
-    # We only assign labels to the PR if we've discovered a list > 1. The labels MUST
-    # already exist. We DO NOT create missing labels.
-    return if pr_labels.empty?
-    $stdout.puts "Attaching the following labels to PR #{pr['number']}: #{pr_labels.join(', ')}"
-    github.add_labels_to_an_issue(repo_path, pr['number'], pr_labels)
   end
 
   def self.update(options)
     options = config_defaults.merge(options)
     defaults = Util.parse_config(File.join(options[:configs], CONF_FILE))
+    if options[:pr]
+      unless options[:branch]
+        $stderr.puts 'A branch must be specified with --branch to use --pr!'
+        raise
+      end
+
+      @pr = create_pr_manager if options[:pr]
+    end
 
     local_template_dir = File.join(options[:configs], MODULE_FILES_DIR)
     local_files = find_template_files(local_template_dir)
@@ -201,4 +168,20 @@ def self.update(options)
     end
     exit 1 if errors && options[:fail_on_warnings]
   end
+
+  def self.create_pr_manager
+    github_token = ENV.fetch('GITHUB_TOKEN', '')
+    gitlab_token = ENV.fetch('GITLAB_TOKEN', '')
+
+    if !github_token.empty?
+      require 'modulesync/pr/github'
+      ModuleSync::PR::GitHub.new(github_token, ENV.fetch('GITHUB_BASE_URL', 'https://api.github.com'))
+    elsif !gitlab_token.empty?
+      require 'modulesync/pr/github'
+      ModuleSync::PR::GitLab.new(gitlab_token, ENV.fetch('GITLAB_BASE_URL', 'https://gitlab.com/api/v4'))
+    else
+      $stderr.puts 'Environment variables GITHUB_TOKEN or GITLAB_TOKEN must be set to use --pr!'
+      raise
+    end
+  end
 end
diff --git a/lib/modulesync/cli.rb b/lib/modulesync/cli.rb
index 2d482a44..fe8d53b1 100644
--- a/lib/modulesync/cli.rb
+++ b/lib/modulesync/cli.rb
@@ -90,14 +90,14 @@ class Base < Thor
              :default => false
       option :pr,
              :type => :boolean,
-             :desc => 'Submit GitHub PR',
+             :desc => 'Submit pull/merge request',
              :default => false
       option :pr_title,
-             :desc => 'Title of GitHub PR',
+             :desc => 'Title of pull/merge request',
              :default => CLI.defaults[:pr_title] || 'Update to module template files'
       option :pr_labels,
              :type => :array,
-             :desc => 'Labels to add to the GitHub PR',
+             :desc => 'Labels to add to the pull/merge request',
              :default => CLI.defaults[:pr_labels] || []
       option :offline,
              :type => :boolean,
diff --git a/lib/modulesync/pr/github.rb b/lib/modulesync/pr/github.rb
new file mode 100644
index 00000000..f352162a
--- /dev/null
+++ b/lib/modulesync/pr/github.rb
@@ -0,0 +1,41 @@
+require 'octokit'
+require 'modulesync/util'
+
+module ModuleSync
+  module PR
+    # GitHub creates and manages pull requests on github.com or GitHub
+    # Enterprise installations.
+    class GitHub
+      def initialize(token, endpoint)
+        Octokit.configure do |c|
+          c.api_endpoint = endpoint
+        end
+        @api = Octokit::Client.new(:access_token => token)
+      end
+
+      def manage(namespace, module_name, options)
+        repo_path = File.join(namespace, module_name)
+        head = "#{namespace}:#{options[:branch]}"
+
+        pull_requests = @api.pull_requests(repo_path, :state => 'open', :base => 'master', :head => head)
+        if pull_requests.empty?
+          pr = @api.create_pull_request(repo_path, 'master', options[:branch], options[:pr_title], options[:message])
+          $stdout.puts "Submitted PR '#{options[:pr_title]}' to #{repo_path} - merges #{options[:branch]} into master"
+        else
+          # Skip creating the PR if it exists already.
+          $stdout.puts "Skipped! #{pull_requests.length} PRs found for branch #{options[:branch]}"
+        end
+
+        # PR labels can either be a list in the YAML file or they can pass in a comma
+        # separated list via the command line argument.
+        pr_labels = ModuleSync::Util.parse_list(options[:pr_labels])
+
+        # We only assign labels to the PR if we've discovered a list > 1. The labels MUST
+        # already exist. We DO NOT create missing labels.
+        return if pr_labels.empty?
+        $stdout.puts "Attaching the following labels to PR #{pr['number']}: #{pr_labels.join(', ')}"
+        @api.add_labels_to_an_issue(repo_path, pr['number'], pr_labels)
+      end
+    end
+  end
+end
diff --git a/lib/modulesync/pr/gitlab.rb b/lib/modulesync/pr/gitlab.rb
new file mode 100644
index 00000000..68ebb335
--- /dev/null
+++ b/lib/modulesync/pr/gitlab.rb
@@ -0,0 +1,40 @@
+require 'gitlab'
+require 'modulesync/util'
+
+module ModuleSync
+  module PR
+    # GitLab creates and manages merge requests on gitlab.com or private GitLab
+    # installations.
+    class GitLab
+      def initialize(token, endpoint)
+        @api = Gitlab::Client.new(
+          :endpoint => endpoint,
+          :private_token => token
+        )
+      end
+
+      def manage(namespace, module_name, options)
+        repo_path = File.join(namespace, module_name)
+
+        head = "#{namespace}:#{options[:branch]}"
+        merge_requests = @api.merge_requests(repo_path,
+                                             :state => 'opened',
+                                             :source_branch => head,
+                                             :target_branch => 'master')
+        if merge_requests.empty?
+          mr_labels = ModuleSync::Util.parse_list(options[:pr_labels])
+          mr = @api.create_merge_request(repo_path, options[:pr_title],
+                                         :source_branch => options[:branch],
+                                         :target_branch => 'master',
+                                         :labels => mr_labels)
+          $stdout.puts "Submitted MR '#{options[:pr_title]}' to #{repo_path} - merges #{options[:branch]} into master"
+          return if mr_labels.empty?
+          $stdout.puts "Attached the following labels to MR #{mr.iid}: #{mr_labels.join(', ')}"
+        else
+          # Skip creating the MR if it exists already.
+          $stdout.puts "Skipped! #{merge_requests.length} MRs found for branch #{options[:branch]}"
+        end
+      end
+    end
+  end
+end
diff --git a/modulesync.gemspec b/modulesync.gemspec
index 293a52d3..16da9be6 100644
--- a/modulesync.gemspec
+++ b/modulesync.gemspec
@@ -24,6 +24,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rubocop', '~> 0.50.0'
 
   spec.add_runtime_dependency 'git', '~>1.3'
+  spec.add_runtime_dependency 'gitlab', '~>4.0'
   spec.add_runtime_dependency 'octokit', '~>4.0'
   spec.add_runtime_dependency 'puppet-blacksmith', '~>3.0'
   spec.add_runtime_dependency 'thor'
diff --git a/spec/unit/modulesync/pr/github_spec.rb b/spec/unit/modulesync/pr/github_spec.rb
new file mode 100644
index 00000000..830c4b05
--- /dev/null
+++ b/spec/unit/modulesync/pr/github_spec.rb
@@ -0,0 +1,49 @@
+require 'spec_helper'
+require 'modulesync/pr/github'
+
+describe ModuleSync::PR::GitHub do
+  context '::manage' do
+    before(:each) do
+      @git_repo = 'test/modulesync'
+      @namespace, @repo_name = @git_repo.split('/')
+      @options = {
+        :pr => true,
+        :pr_title => 'Test PR is submitted',
+        :branch => 'test',
+        :message => 'Hello world',
+        :pr_auto_merge => false,
+      }
+
+      @client = double()
+      allow(Octokit::Client).to receive(:new).and_return(@client)
+      @it = ModuleSync::PR::GitHub.new('test', 'https://api.github.com')
+    end
+
+    it 'submits PR when --pr is set' do
+      allow(@client).to receive(:pull_requests).with(@git_repo, :state => 'open', :base => 'master', :head => "#{@namespace}:#{@options[:branch]}").and_return([])
+      expect(@client).to receive(:create_pull_request).with(@git_repo, 'master', @options[:branch], @options[:pr_title], @options[:message]).and_return({"html_url" => "http://example.com/pulls/22"})
+      expect { @it.manage(@namespace, @repo_name, @options) }.to output(/Submitted PR/).to_stdout
+    end
+
+    it 'skips submitting PR if one has already been issued' do
+      pr = {
+        "title" => "Test title",
+        "html_url" => "https://example.com/pulls/44",
+        "number" => "44"
+      }
+
+      expect(@client).to receive(:pull_requests).with(@git_repo, :state => 'open', :base => 'master', :head => "#{@namespace}:#{@options[:branch]}").and_return([pr])
+      expect { @it.manage(@namespace, @repo_name, @options) }.to output(/Skipped! 1 PRs found for branch test/).to_stdout
+    end
+
+    it 'adds labels to PR when --pr-labels is set' do
+      @options[:pr_labels] = "HELLO,WORLD"
+
+      allow(@client).to receive(:create_pull_request).and_return({"html_url" => "http://example.com/pulls/22", "number" => "44"})
+      allow(@client).to receive(:pull_requests).with(@git_repo, :state => 'open', :base => 'master', :head => "#{@namespace}:#{@options[:branch]}").and_return([])
+
+      expect(@client).to receive(:add_labels_to_an_issue).with(@git_repo, "44", ["HELLO", "WORLD"])
+      expect { @it.manage(@namespace, @repo_name, @options) }.to output(/Attaching the following labels to PR 44: HELLO, WORLD/).to_stdout
+    end
+  end
+end
diff --git a/spec/unit/modulesync/pr/gitlab_spec.rb b/spec/unit/modulesync/pr/gitlab_spec.rb
new file mode 100644
index 00000000..360a773b
--- /dev/null
+++ b/spec/unit/modulesync/pr/gitlab_spec.rb
@@ -0,0 +1,81 @@
+require 'spec_helper'
+require 'modulesync/pr/gitlab'
+
+describe ModuleSync::PR::GitLab do
+  context '::manage' do
+    before(:each) do
+      @git_repo = 'test/modulesync'
+      @namespace, @repo_name = @git_repo.split('/')
+      @options = {
+        :pr => true,
+        :pr_title => 'Test PR is submitted',
+        :branch => 'test',
+        :message => 'Hello world',
+        :pr_auto_merge => false,
+      }
+
+      @client = double()
+      allow(Gitlab::Client).to receive(:new).and_return(@client)
+      @it = ModuleSync::PR::GitLab.new('test', 'https://gitlab.com/api/v4')
+    end
+
+    it 'submits MR when --pr is set' do
+      allow(@client).to receive(:merge_requests)
+        .with(@git_repo,
+              :state => 'opened',
+              :source_branch => "#{@namespace}:#{@options[:branch]}",
+              :target_branch => 'master',
+             ).and_return([])
+
+      expect(@client).to receive(:create_merge_request)
+        .with(@git_repo,
+              @options[:pr_title],
+              :labels => [],
+              :source_branch => @options[:branch],
+              :target_branch => 'master',
+             ).and_return({"html_url" => "http://example.com/pulls/22"})
+
+      expect { @it.manage(@namespace, @repo_name, @options) }.to output(/Submitted MR/).to_stdout
+    end
+
+    it 'skips submitting MR if one has already been issued' do
+      mr = {
+        "title" => "Test title",
+        "html_url" => "https://example.com/pulls/44",
+        "iid" => "44"
+      }
+
+      expect(@client).to receive(:merge_requests)
+        .with(@git_repo,
+              :state => 'opened',
+              :source_branch => "#{@namespace}:#{@options[:branch]}",
+              :target_branch => 'master',
+             ).and_return([mr])
+
+      expect { @it.manage(@namespace, @repo_name, @options) }.to output(/Skipped! 1 MRs found for branch test/).to_stdout
+    end
+
+    it 'adds labels to MR when --pr-labels is set' do
+      @options[:pr_labels] = "HELLO,WORLD"
+      mr = double()
+      allow(mr).to receive(:iid).and_return("42")
+
+      expect(@client).to receive(:create_merge_request)
+        .with(@git_repo,
+              @options[:pr_title],
+              :labels => ["HELLO", "WORLD"],
+              :source_branch => @options[:branch],
+              :target_branch => 'master',
+             ).and_return(mr)
+
+      allow(@client).to receive(:merge_requests)
+        .with(@git_repo,
+              :state => 'opened',
+              :source_branch => "#{@namespace}:#{@options[:branch]}",
+              :target_branch => 'master',
+             ).and_return([])
+
+      expect { @it.manage(@namespace, @repo_name, @options) }.to output(/Attached the following labels to MR 42: HELLO, WORLD/).to_stdout
+    end
+  end
+end
diff --git a/spec/unit/modulesync_spec.rb b/spec/unit/modulesync_spec.rb
index 0b72d104..8197adff 100644
--- a/spec/unit/modulesync_spec.rb
+++ b/spec/unit/modulesync_spec.rb
@@ -12,58 +12,11 @@
     end
   end
 
-  context '::manage_pr' do
-    before(:each) do
-      stub_const('GITHUB_TOKEN', 'test')
-      @git_repo = 'test/modulesync'
-      @namespace, @repo_name = @git_repo.split('/')
-      @options = {
-        :pr => true,
-        :pr_title => 'Test PR is submitted',
-        :branch => 'test',
-        :message => 'Hello world',
-        :pr_auto_merge => false,
-      }
-
-      @client = double()
-    end
-
-    it 'rasies an error when GITHUB_TOKEN not set for PRs' do
-      stub_const('GITHUB_TOKEN', '')
-      options = {:pr => true, :skip_broken => false}
-
-      expect { ModuleSync.manage_pr(@namespace, @repo_name, options) }.to raise_error(RuntimeError).and output(/GITHUB_TOKEN/).to_stderr
-    end
-
-    it 'submits PR when --pr is set' do
-      allow(Octokit::Client).to receive(:new).and_return(@client)
-      allow(@client).to receive(:pull_requests).with(@git_repo, :state => 'open', :base => 'master', :head => "#{@namespace}:#{@options[:branch]}").and_return([])
-      expect(@client).to receive(:create_pull_request).with(@git_repo, 'master', @options[:branch], @options[:pr_title], @options[:message]).and_return({"html_url" => "http://example.com/pulls/22"})
-      expect { ModuleSync.manage_pr(@namespace, @repo_name, @options) }.to output(/Submitted PR/).to_stdout
-    end
-
-    it 'skips submitting PR if one has already been issued' do
-      allow(Octokit::Client).to receive(:new).and_return(@client)
-
-      pr = {
-        "title" => "Test title",
-        "html_url" => "https://example.com/pulls/44",
-        "number" => "44"
-      }
-
-      expect(@client).to receive(:pull_requests).with(@git_repo, :state => 'open', :base => 'master', :head => "#{@namespace}:#{@options[:branch]}").and_return([pr])
-      expect { ModuleSync.manage_pr(@namespace, @repo_name, @options) }.to output(/Skipped! 1 PRs found for branch test/).to_stdout
-    end
-
-    it 'adds labels to PR when --pr-labels is set' do
-      @options[:pr_labels] = "HELLO,WORLD"
-
-      allow(Octokit::Client).to receive(:new).and_return(@client)
-      allow(@client).to receive(:create_pull_request).and_return({"html_url" => "http://example.com/pulls/22", "number" => "44"})
-      allow(@client).to receive(:pull_requests).with(@git_repo, :state => 'open', :base => 'master', :head => "#{@namespace}:#{@options[:branch]}").and_return([])
-
-      expect(@client).to receive(:add_labels_to_an_issue).with(@git_repo, "44", ["HELLO", "WORLD"])
-      expect { ModuleSync.manage_pr(@namespace, @repo_name, @options) }.to output(/Attaching the following labels to PR 44: HELLO, WORLD/).to_stdout
+  context '::create_pr_manager' do
+    describe "Raise Error" do
+      it 'raises an error when neither GITHUB_TOKEN nor GITLAB_TOKEN are set for PRs' do
+        expect { ModuleSync.create_pr_manager() }.to raise_error(RuntimeError).and output(/GITHUB_TOKEN/).to_stderr
+      end
     end
   end
 end