diff --git a/app/assets/javascripts/jobs/components/stages_dropdown.vue b/app/assets/javascripts/jobs/components/stages_dropdown.vue
index c5076d65ff9..6e92b599b0a 100644
--- a/app/assets/javascripts/jobs/components/stages_dropdown.vue
+++ b/app/assets/javascripts/jobs/components/stages_dropdown.vue
@@ -1,5 +1,6 @@
 <script>
 import _ from 'underscore';
+import { GlLink } from '@gitlab/ui';
 import CiIcon from '~/vue_shared/components/ci_icon.vue';
 import Icon from '~/vue_shared/components/icon.vue';
 
@@ -7,6 +8,7 @@ export default {
   components: {
     CiIcon,
     Icon,
+    GlLink,
   },
   props: {
     pipeline: {
@@ -26,6 +28,12 @@ export default {
     hasRef() {
       return !_.isEmpty(this.pipeline.ref);
     },
+    isTriggeredByMergeRequest() {
+      return Boolean(this.pipeline.merge_request);
+    },
+    isMergeRequestPipeline() {
+      return Boolean(this.pipeline.flags && this.pipeline.flags.merge_request_pipeline);
+    },
   },
   methods: {
     onStageClick(stage) {
@@ -36,16 +44,41 @@ export default {
 </script>
 <template>
   <div class="block-last dropdown">
-    <ci-icon :status="pipeline.details.status" class="vertical-align-middle" />
+    <div class="js-pipeline-info">
+      <ci-icon :status="pipeline.details.status" class="vertical-align-middle" />
 
-    <span class="font-weight-bold">{{ __('Pipeline') }}</span>
-    <a :href="pipeline.path" class="js-pipeline-path link-commit qa-pipeline-path"
-      >#{{ pipeline.id }}</a
-    >
-    <template v-if="hasRef">
-      {{ __('from') }}
-      <a :href="pipeline.ref.path" class="link-commit ref-name">{{ pipeline.ref.name }}</a>
-    </template>
+      <span class="font-weight-bold">{{ s__('Job|Pipeline') }}</span>
+      <gl-link :href="pipeline.path" class="js-pipeline-path link-commit qa-pipeline-path"
+        >#{{ pipeline.id }}</gl-link
+      >
+      <template v-if="hasRef">
+        {{ s__('Job|for') }}
+
+        <template v-if="isTriggeredByMergeRequest">
+          <gl-link :href="pipeline.merge_request.path" class="link-commit ref-name js-mr-link"
+            >!{{ pipeline.merge_request.iid }}</gl-link
+          >
+          {{ s__('Job|with') }}
+          <gl-link
+            :href="pipeline.merge_request.source_branch_path"
+            class="link-commit ref-name js-source-branch-link"
+            >{{ pipeline.merge_request.source_branch }}</gl-link
+          >
+
+          <template v-if="isMergeRequestPipeline">
+            {{ s__('Job|into') }}
+            <gl-link
+              :href="pipeline.merge_request.target_branch_path"
+              class="link-commit ref-name js-target-branch-link"
+              >{{ pipeline.merge_request.target_branch }}</gl-link
+            >
+          </template>
+        </template>
+        <gl-link v-else :href="pipeline.ref.path" class="link-commit ref-name">{{
+          pipeline.ref.name
+        }}</gl-link>
+      </template>
+    </div>
 
     <button
       type="button"
diff --git a/changelogs/unreleased/nfriend-update-job-detail-view-sidebar.yml b/changelogs/unreleased/nfriend-update-job-detail-view-sidebar.yml
new file mode 100644
index 00000000000..5364d29710a
--- /dev/null
+++ b/changelogs/unreleased/nfriend-update-job-detail-view-sidebar.yml
@@ -0,0 +1,5 @@
+---
+title: Update job detail sidebar to accommodate post-merge pipeline information
+merge_request: 25777
+author:
+type: added
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index 0dfcf62b36d..c365aea567e 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -4439,6 +4439,9 @@ msgstr ""
 msgid "Job|Keep"
 msgstr ""
 
+msgid "Job|Pipeline"
+msgstr ""
+
 msgid "Job|Scroll to bottom"
 msgstr ""
 
@@ -4457,6 +4460,15 @@ msgstr ""
 msgid "Job|This job is stuck because the project doesn't have any runners online assigned to it."
 msgstr ""
 
+msgid "Job|for"
+msgstr ""
+
+msgid "Job|into"
+msgstr ""
+
+msgid "Job|with"
+msgstr ""
+
 msgid "Jul"
 msgstr ""
 
diff --git a/spec/features/projects/jobs_spec.rb b/spec/features/projects/jobs_spec.rb
index 65ce872363f..224375daf71 100644
--- a/spec/features/projects/jobs_spec.rb
+++ b/spec/features/projects/jobs_spec.rb
@@ -2,6 +2,9 @@ require 'spec_helper'
 require 'tempfile'
 
 describe 'Jobs', :clean_gitlab_redis_shared_state do
+  include Gitlab::Routing
+  include ProjectForksHelper
+
   let(:user) { create(:user) }
   let(:user_access_level) { :developer }
   let(:project) { create(:project, :repository) }
@@ -121,6 +124,112 @@ describe 'Jobs', :clean_gitlab_redis_shared_state do
       end
     end
 
+    context 'pipeline info block', :js do
+      it 'shows pipeline id and source branch' do
+        visit project_job_path(project, job)
+
+        within '.js-pipeline-info' do
+          expect(page).to have_content("Pipeline ##{pipeline.id} for #{pipeline.ref}")
+        end
+      end
+
+      context 'when pipeline is detached merge request pipeline' do
+        let(:merge_request) do
+          create(:merge_request,
+            :with_detached_merge_request_pipeline,
+            target_project: target_project,
+            source_project: source_project)
+        end
+
+        let(:source_project) { project }
+        let(:target_project) { project }
+        let(:pipeline) { merge_request.all_pipelines.last }
+        let(:job) { create(:ci_build, pipeline: pipeline) }
+
+        it 'shows merge request iid and source branch' do
+          visit project_job_path(project, job)
+
+          within '.js-pipeline-info' do
+            expect(page).to have_content("for !#{pipeline.merge_request.iid} " \
+                                         "with #{pipeline.merge_request.source_branch}")
+            expect(page).to have_link("!#{pipeline.merge_request.iid}",
+              href: project_merge_request_path(project, merge_request))
+            expect(page).to have_link(pipeline.merge_request.source_branch,
+              href: project_commits_path(project, merge_request.source_branch))
+          end
+        end
+
+        context 'when source project is a forked project' do
+          let(:source_project) { fork_project(project, user, repository: true) }
+          let(:target_project) { project }
+
+          it 'shows merge request iid and source branch' do
+            visit project_job_path(source_project, job)
+
+            within '.js-pipeline-info' do
+              expect(page).to have_content("for !#{pipeline.merge_request.iid} " \
+                                           "with #{pipeline.merge_request.source_branch}")
+              expect(page).to have_link("!#{pipeline.merge_request.iid}",
+                href: project_merge_request_path(project, merge_request))
+              expect(page).to have_link(pipeline.merge_request.source_branch,
+                href: project_commits_path(source_project, merge_request.source_branch))
+            end
+          end
+        end
+      end
+
+      context 'when pipeline is merge request pipeline' do
+        let(:merge_request) do
+          create(:merge_request,
+            :with_merge_request_pipeline,
+            target_project: target_project,
+            source_project: source_project)
+        end
+
+        let(:source_project) { project }
+        let(:target_project) { project }
+        let(:pipeline) { merge_request.all_pipelines.last }
+        let(:job) { create(:ci_build, pipeline: pipeline) }
+
+        it 'shows merge request iid and source branch' do
+          visit project_job_path(project, job)
+
+          within '.js-pipeline-info' do
+            expect(page).to have_content("for !#{pipeline.merge_request.iid} " \
+                                         "with #{pipeline.merge_request.source_branch} " \
+                                         "into #{pipeline.merge_request.target_branch}")
+            expect(page).to have_link("!#{pipeline.merge_request.iid}",
+              href: project_merge_request_path(project, merge_request))
+            expect(page).to have_link(pipeline.merge_request.source_branch,
+              href: project_commits_path(project, merge_request.source_branch))
+            expect(page).to have_link(pipeline.merge_request.target_branch,
+              href: project_commits_path(project, merge_request.target_branch))
+          end
+        end
+
+        context 'when source project is a forked project' do
+          let(:source_project) { fork_project(project, user, repository: true) }
+          let(:target_project) { project }
+
+          it 'shows merge request iid and source branch' do
+            visit project_job_path(source_project, job)
+
+            within '.js-pipeline-info' do
+              expect(page).to have_content("for !#{pipeline.merge_request.iid} " \
+                                           "with #{pipeline.merge_request.source_branch} " \
+                                           "into #{pipeline.merge_request.target_branch}")
+              expect(page).to have_link("!#{pipeline.merge_request.iid}",
+                href: project_merge_request_path(project, merge_request))
+              expect(page).to have_link(pipeline.merge_request.source_branch,
+                href: project_commits_path(source_project, merge_request.source_branch))
+              expect(page).to have_link(pipeline.merge_request.target_branch,
+                href: project_commits_path(project, merge_request.target_branch))
+            end
+          end
+        end
+      end
+    end
+
     context 'sidebar', :js do
       let(:job) { create(:ci_build, :success, :trace_live, pipeline: pipeline, name: '<img src=x onerror=alert(document.domain)>') }
 
diff --git a/spec/javascripts/jobs/components/stages_dropdown_spec.js b/spec/javascripts/jobs/components/stages_dropdown_spec.js
index 9c731ae2f68..eccb4e13d67 100644
--- a/spec/javascripts/jobs/components/stages_dropdown_spec.js
+++ b/spec/javascripts/jobs/components/stages_dropdown_spec.js
@@ -1,59 +1,167 @@
 import Vue from 'vue';
 import component from '~/jobs/components/stages_dropdown.vue';
+import { trimText } from 'spec/helpers/vue_component_helper';
 import mountComponent from '../../helpers/vue_mount_component_helper';
 
 describe('Stages Dropdown', () => {
   const Component = Vue.extend(component);
   let vm;
 
-  beforeEach(() => {
-    vm = mountComponent(Component, {
-      pipeline: {
-        id: 28029444,
-        details: {
-          status: {
-            details_path: '/gitlab-org/gitlab-ce/pipelines/28029444',
-            group: 'success',
-            has_details: true,
-            icon: 'status_success',
-            label: 'passed',
-            text: 'passed',
-            tooltip: 'passed',
-          },
-        },
-        path: 'pipeline/28029444',
+  const mockPipelineData = {
+    id: 28029444,
+    details: {
+      status: {
+        details_path: '/gitlab-org/gitlab-ce/pipelines/28029444',
+        group: 'success',
+        has_details: true,
+        icon: 'status_success',
+        label: 'passed',
+        text: 'passed',
+        tooltip: 'passed',
       },
-      stages: [
-        {
-          name: 'build',
-        },
-        {
-          name: 'test',
-        },
-      ],
-      selectedStage: 'deploy',
+    },
+    path: 'pipeline/28029444',
+    flags: {
+      merge_request_pipeline: true,
+      detached_merge_request_pipeline: false,
+    },
+    merge_request: {
+      iid: 1234,
+      path: '/root/detached-merge-request-pipelines/merge_requests/1',
+      title: 'Update README.md',
+      source_branch: 'feature-1234',
+      source_branch_path: '/root/detached-merge-request-pipelines/branches/feature-1234',
+      target_branch: 'master',
+      target_branch_path: '/root/detached-merge-request-pipelines/branches/master',
+    },
+    ref: {
+      name: 'test-branch',
+    },
+  };
+
+  describe('without a merge request pipeline', () => {
+    let pipeline;
+
+    beforeEach(() => {
+      pipeline = JSON.parse(JSON.stringify(mockPipelineData));
+      delete pipeline.merge_request;
+      delete pipeline.flags.merge_request_pipeline;
+      delete pipeline.flags.detached_merge_request_pipeline;
+
+      vm = mountComponent(Component, {
+        pipeline,
+        stages: [{ name: 'build' }, { name: 'test' }],
+        selectedStage: 'deploy',
+      });
+    });
+
+    afterEach(() => {
+      vm.$destroy();
+    });
+
+    it('renders pipeline status', () => {
+      expect(vm.$el.querySelector('.js-ci-status-icon-success')).not.toBeNull();
+    });
+
+    it('renders pipeline link', () => {
+      expect(vm.$el.querySelector('.js-pipeline-path').getAttribute('href')).toEqual(
+        'pipeline/28029444',
+      );
+    });
+
+    it('renders dropdown with stages', () => {
+      expect(vm.$el.querySelector('.dropdown .js-stage-item').textContent).toContain('build');
+    });
+
+    it('rendes selected stage', () => {
+      expect(vm.$el.querySelector('.dropdown .js-selected-stage').textContent).toContain('deploy');
+    });
+
+    it(`renders the pipeline info text like "Pipeline #123 for source_branch"`, () => {
+      const expected = `Pipeline #${pipeline.id} for ${pipeline.ref.name}`;
+      const actual = trimText(vm.$el.querySelector('.js-pipeline-info').innerText);
+
+      expect(actual).toBe(expected);
     });
   });
 
-  afterEach(() => {
-    vm.$destroy();
+  describe('with an "attached" merge request pipeline', () => {
+    let pipeline;
+
+    beforeEach(() => {
+      pipeline = JSON.parse(JSON.stringify(mockPipelineData));
+      pipeline.flags.merge_request_pipeline = true;
+      pipeline.flags.detached_merge_request_pipeline = false;
+
+      vm = mountComponent(Component, {
+        pipeline,
+        stages: [],
+        selectedStage: 'deploy',
+      });
+    });
+
+    it(`renders the pipeline info text like "Pipeline #123 for !456 with source_branch into target_branch"`, () => {
+      const expected = `Pipeline #${pipeline.id} for !${pipeline.merge_request.iid} with ${
+        pipeline.merge_request.source_branch
+      } into ${pipeline.merge_request.target_branch}`;
+      const actual = trimText(vm.$el.querySelector('.js-pipeline-info').innerText);
+
+      expect(actual).toBe(expected);
+    });
+
+    it(`renders the correct merge request link`, () => {
+      const actual = vm.$el.querySelector('.js-mr-link').href;
+
+      expect(actual).toContain(pipeline.merge_request.path);
+    });
+
+    it(`renders the correct source branch link`, () => {
+      const actual = vm.$el.querySelector('.js-source-branch-link').href;
+
+      expect(actual).toContain(pipeline.merge_request.source_branch_path);
+    });
+
+    it(`renders the correct target branch link`, () => {
+      const actual = vm.$el.querySelector('.js-target-branch-link').href;
+
+      expect(actual).toContain(pipeline.merge_request.target_branch_path);
+    });
   });
 
-  it('renders pipeline status', () => {
-    expect(vm.$el.querySelector('.js-ci-status-icon-success')).not.toBeNull();
-  });
+  describe('with a detached merge request pipeline', () => {
+    let pipeline;
 
-  it('renders pipeline link', () => {
-    expect(vm.$el.querySelector('.js-pipeline-path').getAttribute('href')).toEqual(
-      'pipeline/28029444',
-    );
-  });
+    beforeEach(() => {
+      pipeline = JSON.parse(JSON.stringify(mockPipelineData));
+      pipeline.flags.merge_request_pipeline = false;
+      pipeline.flags.detached_merge_request_pipeline = true;
 
-  it('renders dropdown with stages', () => {
-    expect(vm.$el.querySelector('.dropdown .js-stage-item').textContent).toContain('build');
-  });
+      vm = mountComponent(Component, {
+        pipeline,
+        stages: [],
+        selectedStage: 'deploy',
+      });
+    });
 
-  it('rendes selected stage', () => {
-    expect(vm.$el.querySelector('.dropdown .js-selected-stage').textContent).toContain('deploy');
+    it(`renders the pipeline info like "Pipeline #123 for !456 with source_branch"`, () => {
+      const expected = `Pipeline #${pipeline.id} for !${pipeline.merge_request.iid} with ${
+        pipeline.merge_request.source_branch
+      }`;
+      const actual = trimText(vm.$el.querySelector('.js-pipeline-info').innerText);
+
+      expect(actual).toBe(expected);
+    });
+
+    it(`renders the correct merge request link`, () => {
+      const actual = vm.$el.querySelector('.js-mr-link').href;
+
+      expect(actual).toContain(pipeline.merge_request.path);
+    });
+
+    it(`renders the correct source branch link`, () => {
+      const actual = vm.$el.querySelector('.js-source-branch-link').href;
+
+      expect(actual).toContain(pipeline.merge_request.source_branch_path);
+    });
   });
 });