diff --git a/CHANGELOG b/CHANGELOG
index 441f36a5bde41d597193f96ea332bbff561bfef3..2a025d6481e665a9ed83e9321756c93448cd8c04 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,12 @@
+v 6.8.0
+  - Ability to at mention users that are participating in issue and merge req. discussion
+
+v 6.7.2
+  - Fix upgrader script
+
+v 6.7.1
+  - Fix GitLab CI integration
+
 v 6.7.0
   - Increased the example Nginx client_max_body_size from 5MB to 20MB, consider updating it manually on existing installations
   - Add support for Gemnasium as a Project Service (Olivier Gonzalez)
diff --git a/VERSION b/VERSION
index f0e13c509025821bc44ae215533a6d4d332154d0..2dd517aa61c31a26b2f3e017e84c0ac028804aca 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.7.0
+6.7.2
diff --git a/app/controllers/projects_controller.rb b/app/controllers/projects_controller.rb
index e181a0ec7fa05109556439462be50fbb3658a7af..ebb8a90c630039ace5730de753303406c5ba70e2 100644
--- a/app/controllers/projects_controller.rb
+++ b/app/controllers/projects_controller.rb
@@ -123,11 +123,20 @@ class ProjectsController < ApplicationController
   end
 
   def autocomplete_sources
+    note_type = params['type']
+    note_id = params['type_id']
+    participating = if note_type && note_id
+                      participants_in(note_type, note_id)
+                    else
+                      []
+                    end
+    team_members = sorted(@project.team.members)
+    participants = team_members + participating
     @suggestions = {
       emojis: Emoji.names.map { |e| { name: e, path: view_context.image_url("emoji/#{e}.png") } },
       issues: @project.issues.select([:iid, :title, :description]),
       mergerequests: @project.merge_requests.select([:iid, :title, :description]),
-      members: @project.team.members.sort_by(&:username).map { |user| { username: user.username, name: user.name } }
+      members: participants.uniq
     }
 
     respond_to do |format|
@@ -162,4 +171,25 @@ class ProjectsController < ApplicationController
   def user_layout
     current_user ? "projects" : "public_projects"
   end
+
+  def participants_in(type, id)
+    users = case type
+            when "Issue"
+              issue = @project.issues.find_by_iid(id)
+              issue ? issue.participants : []
+            when "MergeRequest"
+              merge_request = @project.merge_requests.find_by_iid(id)
+              merge_request ? merge_request.participants : []
+            when "Commit"
+              author_ids = Note.for_commit_id(id).pluck(:author_id).uniq
+              User.where(id: author_ids)
+            else
+              []
+            end
+    sorted(users)
+  end
+
+  def sorted(users)
+    users.uniq.sort_by(&:username).map { |user| { username: user.username, name: user.name } }
+  end
 end
diff --git a/app/views/layouts/_init_auto_complete.html.haml b/app/views/layouts/_init_auto_complete.html.haml
index 9e728b462bbe7c6253543e4ada083343c819e7e0..353f7ce34f1273604f4d6a9aa08d646c8e3c79a5 100644
--- a/app/views/layouts/_init_auto_complete.html.haml
+++ b/app/views/layouts/_init_auto_complete.html.haml
@@ -1,3 +1,3 @@
 :javascript
-  GitLab.GfmAutoComplete.dataSource = "#{autocomplete_sources_project_path(@project)}"
+  GitLab.GfmAutoComplete.dataSource = "#{autocomplete_sources_project_path(@project, type: @noteable.class, type_id: params[:id])}"
   GitLab.GfmAutoComplete.setup();
diff --git a/lib/gitlab/markdown.rb b/lib/gitlab/markdown.rb
index 80bb00821f74fea51781888dcfa944a6186d3fea..de14a3eca275611cf7ada45224116049f31bf8e7 100644
--- a/lib/gitlab/markdown.rb
+++ b/lib/gitlab/markdown.rb
@@ -166,8 +166,8 @@ module Gitlab
     end
 
     def reference_user(identifier)
-      if member = @project.team_members.find { |user| user.username == identifier }
-        link_to("@#{identifier}", user_url(identifier), html_options.merge(class: "gfm gfm-team_member #{html_options[:class]}")) if member
+      if user = User.find_by_username(identifier)
+        link_to("@#{identifier}", user_url(identifier), html_options.merge(class: "gfm gfm-team_member #{html_options[:class]}"))
       end
     end