diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.html b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
index a6e1b40ff2..00157abb88 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.html
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
@@ -16,6 +16,7 @@ limitations under the License.
 -->
 
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
+<link rel="import" href="../../../bower_components/iron-icon/iron-icon.html">
 <link rel="import" href="../../shared/gr-account-label/gr-account-label.html">
 <link rel="import" href="../../shared/gr-button/gr-button.html">
 <link rel="import" href="../../shared/gr-date-formatter/gr-date-formatter.html">
@@ -115,7 +116,7 @@ limitations under the License.
         overflow: hidden;
         text-overflow: ellipsis;
       }
-      .collapsed .date {
+      .collapsed .dateContainer {
         position: static;
       }
       .collapsed .author {
@@ -126,12 +127,17 @@ limitations under the License.
         cursor: pointer;
         margin-bottom: .4em;
       }
-      .date {
-        color: var(--deemphasized-text-color);
+      .dateContainer {
         position: absolute;
         right: var(--default-horizontal-margin);
         top: 10px;
       }
+      .date {
+        color: var(--deemphasized-text-color);
+      }
+      .dateContainer iron-icon {
+        cursor: pointer;
+      }
       .replyContainer {
         padding: .5em 0 0 0;
       }
@@ -211,22 +217,29 @@ limitations under the License.
             </template>
           </div>
         </template>
-        <template is="dom-if" if="[[!message.id]]">
-          <span class="date">
-            <gr-date-formatter
-                has-tooltip
-                show-date-and-time
-                date-str="[[message.date]]"></gr-date-formatter>
-          </span>
-        </template>
-        <template is="dom-if" if="[[message.id]]">
-          <a class="date" href$="[[_computeMessageHash(message)]]" on-tap="_handleLinkTap">
-            <gr-date-formatter
-                has-tooltip
-                show-date-and-time
-                date-str="[[message.date]]"></gr-date-formatter>
-          </a>
-        </template>
+        <span class="dateContainer">
+          <template is="dom-if" if="[[!message.id]]">
+            <span class="date">
+              <gr-date-formatter
+                  has-tooltip
+                  show-date-and-time
+                  date-str="[[message.date]]"></gr-date-formatter>
+            </span>
+          </template>
+          <template is="dom-if" if="[[message.id]]">
+            <a class="date" href$="[[_computeMessageHash(message)]]" on-tap="_handleLinkTap">
+              <gr-date-formatter
+                  has-tooltip
+                  show-date-and-time
+                  date-str="[[message.date]]"></gr-date-formatter>
+            </a>
+          </template>
+          <iron-icon
+              id="expandToggle"
+              on-tap="_toggleExpanded"
+              title="Toggle expanded state"
+              icon="[[_computeExpandToggleIcon(_expanded)]]">
+        </span>
       </div>
     </div>
     <gr-rest-api-interface id="restAPI"></gr-rest-api-interface>
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.js b/polygerrit-ui/app/elements/change/gr-message/gr-message.js
index a6d4b034e0..0590c73eb4 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.js
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.js
@@ -251,5 +251,14 @@
         this._projectConfig = config;
       });
     },
+
+    _computeExpandToggleIcon(expanded) {
+      return expanded ? 'gr-icons:expand-less' : 'gr-icons:expand-more';
+    },
+
+    _toggleExpanded(e) {
+      e.stopPropagation();
+      this.set('message.expanded', !this.message.expanded);
+    },
   });
 })();