diff --git a/CHANGELOG b/CHANGELOG
index 3e30123e464..121cf1b1933 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -4,6 +4,7 @@ v 8.3.0 (unreleased)
   - Add CAS support (tduehr)
   - Bump rack-attack to 4.3.1 for security fix (Stan Hu)
   - API support for starred projects for authorized user (Zeger-Jan van de Weg)
+  - Add link to merge request on build detail page.
   - Add open_issues_count to project API (Stan Hu)
   - Expand character set of usernames created by Omniauth (Corey Hinshaw)
   - Add button to automatically merge a merge request when the build succeeds (Zeger-Jan van de Weg)
diff --git a/app/models/ci/build.rb b/app/models/ci/build.rb
index 470b97a3c0f..7b89fe069ea 100644
--- a/app/models/ci/build.rb
+++ b/app/models/ci/build.rb
@@ -135,6 +135,16 @@ module Ci
       predefined_variables + yaml_variables + project_variables + trigger_variables
     end
 
+    def merge_request
+      merge_requests = MergeRequest.includes(:merge_request_diff)
+                                   .where(source_branch: ref, source_project_id: commit.gl_project_id)
+                                   .reorder(iid: :asc)
+
+      merge_requests.find do |merge_request|
+        merge_request.commits.any? { |ci| ci.id == commit.sha }
+      end
+    end
+
     def project
       commit.project
     end
diff --git a/app/views/projects/builds/show.html.haml b/app/views/projects/builds/show.html.haml
index 20a5b6a66e7..5b7ecce86ab 100644
--- a/app/views/projects/builds/show.html.haml
+++ b/app/views/projects/builds/show.html.haml
@@ -7,6 +7,10 @@
     %strong.monospace= link_to @build.commit.short_sha, ci_status_path(@build.commit)
     from
     = link_to @build.ref, namespace_project_commits_path(@project.namespace, @project, @build.ref)
+    - merge_request = @build.merge_request
+    - if merge_request
+      via
+      = link_to "merge request ##{merge_request.iid}", merge_request_path(merge_request)
 
   #up-build-trace
   - if @commit.matrix_for_ref?(@build.ref)
diff --git a/spec/models/build_spec.rb b/spec/models/build_spec.rb
index e3880cd9cfe..1c22e3cb7c4 100644
--- a/spec/models/build_spec.rb
+++ b/spec/models/build_spec.rb
@@ -396,4 +396,68 @@ describe Ci::Build, models: true do
     it { is_expected.to include('gitlab-ci-token') }
     it { is_expected.to include(project.web_url[7..-1]) }
   end
+
+  def create_mr(build, commit, factory: :merge_request, created_at: Time.now)
+    FactoryGirl.create(factory,
+                       source_project_id: commit.gl_project_id,
+                       target_project_id: commit.gl_project_id,
+                       source_branch: build.ref,
+                       created_at: created_at)
+  end
+
+  describe :merge_request do
+    context 'when a MR has a reference to the commit' do
+      before do
+        @merge_request = create_mr(build, commit, factory: :merge_request)
+
+        commits = [double(id: commit.sha)]
+        allow(@merge_request).to receive(:commits).and_return(commits)
+        allow(MergeRequest).to receive_message_chain(:includes, :where, :reorder).and_return([@merge_request])
+      end
+
+      it 'returns the single associated MR' do
+        expect(build.merge_request.id).to eq(@merge_request.id)
+      end
+    end
+
+    context 'when there is not a MR referencing the commit' do
+      it 'returns nil' do
+        expect(build.merge_request).to be_nil
+      end
+    end
+
+    context 'when more than one MR have a reference to the commit' do
+      before do
+        @merge_request = create_mr(build, commit, factory: :merge_request)
+        @merge_request.close!
+        @merge_request2 = create_mr(build, commit, factory: :merge_request)
+
+        commits = [double(id: commit.sha)]
+        allow(@merge_request).to receive(:commits).and_return(commits)
+        allow(@merge_request2).to receive(:commits).and_return(commits)
+        allow(MergeRequest).to receive_message_chain(:includes, :where, :reorder).and_return([@merge_request, @merge_request2])
+      end
+
+      it 'returns the first MR' do
+        expect(build.merge_request.id).to eq(@merge_request.id)
+      end
+    end
+
+    context 'when a Build is created after the MR' do
+      before do
+        @merge_request = create_mr(build, commit, factory: :merge_request_with_diffs)
+        commit2 = FactoryGirl.create :ci_commit, project: project
+        @build2 = FactoryGirl.create :ci_build, commit: commit2
+
+        commits = [double(id: commit.sha), double(id: commit2.sha)]
+        allow(@merge_request).to receive(:commits).and_return(commits)
+        allow(MergeRequest).to receive_message_chain(:includes, :where, :reorder).and_return([@merge_request])
+      end
+
+      it 'returns the current MR' do
+        expect(@build2.merge_request.id).to eq(@merge_request.id)
+      end
+    end
+
+  end
 end