--- a/browser/base/content/browser-siteIdentity.js
+++ b/browser/base/content/browser-siteIdentity.js
@@ -196,26 +196,63 @@ var gIdentityHandler = {
   get _permissionReloadHint() {
     delete this._permissionReloadHint;
     return this._permissionReloadHint = document.getElementById("identity-popup-permission-reload-hint");
   },
   get _popupExpander() {
     delete this._popupExpander;
     return this._popupExpander = document.getElementById("identity-popup-security-expander");
   },
+  get _clearSiteDataFooter() {
+    delete this._clearSiteDataFooter;
+    return this._clearSiteDataFooter = document.getElementById("identity-popup-clear-sitedata-footer");
+  },
   get _permissionAnchors() {
     delete this._permissionAnchors;
     let permissionAnchors = {};
     for (let anchor of document.getElementById("blocked-permissions-container").children) {
       permissionAnchors[anchor.getAttribute("data-permission-id")] = anchor;
     }
     return this._permissionAnchors = permissionAnchors;
   },
 
   /**
+   * Handles clicks on the "Clear Cookies and Site Data" button.
+   */
+  async clearSiteData(event) {
+    if (!this._uriHasHost) {
+      return;
+    }
+
+    let host = this._uri.host;
+
+    // Site data could have changed while the identity popup was open,
+    // reload again to be sure.
+    await SiteDataManager.updateSites();
+
+    let baseDomain = SiteDataManager.getBaseDomainFromHost(host);
+    let siteData = await SiteDataManager.getSites(baseDomain);
+
+    // Hide the popup before showing the removal prompt, to
+    // avoid a pretty ugly transition. Also hide it even
+    // if the update resulted in no site data, to keep the
+    // illusion that clicking the button had an effect.
+    PanelMultiView.hidePopup(this._identityPopup);
+
+    if (siteData && siteData.length) {
+      let hosts = siteData.map(site => site.host);
+      if (SiteDataManager.promptSiteDataRemoval(window, hosts)) {
+        SiteDataManager.remove(hosts);
+      }
+    }
+
+    event.stopPropagation();
+  },
+
+  /**
    * Handler for mouseclicks on the "More Information" button in the
    * "identity-popup" panel.
    */
   handleMoreInfoClick(event) {
     displaySecurityInfo();
     event.stopPropagation();
     PanelMultiView.hidePopup(this._identityPopup);
   },
@@ -573,16 +610,31 @@ var gIdentityHandler = {
   },
 
   /**
    * Set up the title and content messages for the identity message popup,
    * based on the specified mode, and the details of the SSL cert, where
    * applicable
    */
   refreshIdentityPopup() {
+    // Update cookies and site data information and show the
+    // "Clear Site Data" button if the site is storing local data.
+    this._clearSiteDataFooter.hidden = true;
+    if (this._uriHasHost) {
+      let host = this._uri.host;
+      SiteDataManager.updateSites().then(async () => {
+        let baseDomain = SiteDataManager.getBaseDomainFromHost(host);
+        let siteData = await SiteDataManager.getSites(baseDomain);
+
+        if (siteData && siteData.length) {
+          this._clearSiteDataFooter.hidden = false;
+        }
+      });
+    }
+
     // Update "Learn More" for Mixed Content Blocking and Insecure Login Forms.
     let baseURL = Services.urlFormatter.formatURLPref("app.support.baseURL");
     this._identityPopupMixedContentLearnMore
         .setAttribute("href", baseURL + "mixed-content");
     this._identityPopupInsecureLoginFormsLearnMore
         .setAttribute("href", baseURL + "insecure-password");
 
     // This is in the properties file because the expander used to switch its tooltip.

--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -50,16 +50,17 @@ XPCOMUtils.defineLazyModuleGetters(this,
   ReaderMode: "resource://gre/modules/ReaderMode.jsm",
   ReaderParent: "resource:///modules/ReaderParent.jsm",
   SafeBrowsing: "resource://gre/modules/SafeBrowsing.jsm",
   Sanitizer: "resource:///modules/Sanitizer.jsm",
   SessionStore: "resource:///modules/sessionstore/SessionStore.jsm",
   SchedulePressure: "resource:///modules/SchedulePressure.jsm",
   ShortcutUtils: "resource://gre/modules/ShortcutUtils.jsm",
   SimpleServiceDiscovery: "resource://gre/modules/SimpleServiceDiscovery.jsm",
+  SiteDataManager: "resource:///modules/SiteDataManager.jsm",
   SitePermissions: "resource:///modules/SitePermissions.jsm",
   TabCrashHandler: "resource:///modules/ContentCrashHandlers.jsm",
   TelemetryStopwatch: "resource://gre/modules/TelemetryStopwatch.jsm",
   Translation: "resource:///modules/translation/Translation.jsm",
   UITour: "resource:///modules/UITour.jsm",
   UpdateUtils: "resource://gre/modules/UpdateUtils.jsm",
   Utils: "resource://gre/modules/sessionstore/Utils.jsm",
   Weave: "resource://services-sync/main.js",

--- a/browser/base/content/test/siteIdentity/browser.ini
+++ b/browser/base/content/test/siteIdentity/browser.ini
@@ -41,16 +41,17 @@ support-files =
 [browser_csp_block_all_mixedcontent.js]
 tags = mcb
 support-files =
   file_csp_block_all_mixedcontent.html
   file_csp_block_all_mixedcontent.js
 [browser_identity_UI.js]
 [browser_identityBlock_focus.js]
 support-files = ../permissions/permissions.html
+[browser_identityPopup_clearSiteData.js]
 [browser_identityPopup_focus.js]
 [browser_insecureLoginForms.js]
 support-files =
   insecure_opener.html
   !/toolkit/components/passwordmgr/test/browser/form_basic.html
   !/toolkit/components/passwordmgr/test/browser/insecure_test.html
   !/toolkit/components/passwordmgr/test/browser/insecure_test_subframe.html
 [browser_mcb_redirect.js]

new file mode 100644
--- /dev/null
+++ b/browser/base/content/test/siteIdentity/browser_identityPopup_clearSiteData.js
@@ -0,0 +1,110 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const TEST_ORIGIN = "https://example.com";
+const TEST_SUB_ORIGIN = "https://test1.example.com";
+const REMOVE_DIALOG_URL = "chrome://browser/content/preferences/siteDataRemoveSelected.xul";
+
+ChromeUtils.defineModuleGetter(this, "SiteDataTestUtils",
+                               "resource://testing-common/SiteDataTestUtils.jsm");
+
+async function testClearing(testQuota, testCookies) {
+  // Add some test quota storage.
+  if (testQuota) {
+    await SiteDataTestUtils.addToIndexedDB(TEST_ORIGIN);
+    await SiteDataTestUtils.addToIndexedDB(TEST_SUB_ORIGIN);
+  }
+
+  // Add some test cookies.
+  if (testCookies) {
+    SiteDataTestUtils.addToCookies(TEST_ORIGIN, "test1", "1");
+    SiteDataTestUtils.addToCookies(TEST_ORIGIN, "test2", "2");
+    SiteDataTestUtils.addToCookies(TEST_SUB_ORIGIN, "test3", "1");
+  }
+
+  await BrowserTestUtils.withNewTab(TEST_ORIGIN, async function(browser) {
+    // Verify we have added quota storage.
+    if (testQuota) {
+      let usage = await SiteDataTestUtils.getQuotaUsage(TEST_ORIGIN);
+      Assert.greater(usage, 0, "Should have data for the base origin.");
+
+      usage = await SiteDataTestUtils.getQuotaUsage(TEST_SUB_ORIGIN);
+      Assert.greater(usage, 0, "Should have data for the sub origin.");
+    }
+
+    // Open the identity popup.
+    let { gIdentityHandler } = gBrowser.ownerGlobal;
+    let promisePanelOpen = BrowserTestUtils.waitForEvent(gIdentityHandler._identityPopup, "popupshown");
+    let siteDataUpdated = TestUtils.topicObserved("sitedatamanager:sites-updated");
+    gIdentityHandler._identityBox.click();
+    await promisePanelOpen;
+    await siteDataUpdated;
+
+    let clearFooter = document.getElementById("identity-popup-clear-sitedata-footer");
+    let clearButton = document.getElementById("identity-popup-clear-sitedata-button");
+    ok(!clearFooter.hidden, "The clear data footer is not hidden.");
+
+    let cookiesCleared;
+    if (testCookies) {
+      cookiesCleared = Promise.all([
+        TestUtils.topicObserved("cookie-changed", (subj, data) => data == "deleted" && subj.name == "test1"),
+        TestUtils.topicObserved("cookie-changed", (subj, data) => data == "deleted" && subj.name == "test2"),
+        TestUtils.topicObserved("cookie-changed", (subj, data) => data == "deleted" && subj.name == "test3"),
+      ]);
+    }
+
+    // Click the "Clear data" button.
+    siteDataUpdated = TestUtils.topicObserved("sitedatamanager:sites-updated");
+    let hideEvent = BrowserTestUtils.waitForEvent(gIdentityHandler._identityPopup, "popuphidden");
+    let removeDialogPromise = BrowserTestUtils.promiseAlertDialogOpen("accept", REMOVE_DIALOG_URL);
+    clearButton.click();
+    await hideEvent;
+    await removeDialogPromise;
+
+    await siteDataUpdated;
+
+    // Check that cookies were deleted.
+    if (testCookies) {
+      await cookiesCleared;
+      let uri = Services.io.newURI(TEST_ORIGIN);
+      is(Services.cookies.countCookiesFromHost(uri.host), 0, "Cookies from the base domain should be cleared");
+      uri = Services.io.newURI(TEST_SUB_ORIGIN);
+      is(Services.cookies.countCookiesFromHost(uri.host), 0, "Cookies from the sub domain should be cleared");
+    }
+
+    // Check that quota storage was deleted.
+    if (testQuota) {
+      await TestUtils.waitForCondition(async () => {
+        let usage = await SiteDataTestUtils.getQuotaUsage(TEST_ORIGIN);
+        return usage == 0;
+      }, "Should have no data for the base origin.");
+
+      let usage = await SiteDataTestUtils.getQuotaUsage(TEST_SUB_ORIGIN);
+      is(usage, 0, "Should have no data for the sub origin.");
+    }
+
+    // Open the site identity panel again to check that the button isn't shown anymore.
+    promisePanelOpen = BrowserTestUtils.waitForEvent(gIdentityHandler._identityPopup, "popupshown");
+    siteDataUpdated = TestUtils.topicObserved("sitedatamanager:sites-updated");
+    gIdentityHandler._identityBox.click();
+    await promisePanelOpen;
+    await siteDataUpdated;
+
+    ok(clearFooter.hidden, "The clear data footer is hidden after clearing data.");
+  });
+}
+
+// Test removing quota managed storage.
+add_task(async function test_ClearSiteData() {
+  await testClearing(true, false);
+});
+
+// Test removing cookies.
+add_task(async function test_ClearCookies() {
+  await testClearing(false, true);
+});
+
+// Test removing both.
+add_task(async function test_ClearCookiesAndSiteData() {
+  await testClearing(true, true);
+});

--- a/browser/components/controlcenter/content/panel.inc.xul
+++ b/browser/components/controlcenter/content/panel.inc.xul
@@ -90,16 +90,26 @@
           <label id="identity-popup-permissions-headline"
                  class="identity-popup-headline"
                  value="&identity.permissions;"/>
           <vbox id="identity-popup-permission-list"/>
           <description id="identity-popup-permission-reload-hint">&identity.permissionsReloadHint;</description>
           <description id="identity-popup-permission-empty-hint">&identity.permissionsEmpty;</description>
         </vbox>
       </hbox>
+
+      <!-- Clear Site Data Button -->
+      <vbox hidden="true"
+            id="identity-popup-clear-sitedata-footer"
+            class="identity-popup-footer">
+        <button class="subviewkeynav"
+                id="identity-popup-clear-sitedata-button"
+                label="&identity.clearSiteData;"
+                oncommand="gIdentityHandler.clearSiteData(event);"/>
+      </vbox>
     </panelview>
 
     <!-- Security SubView -->
     <panelview id="identity-popup-securityView"
                title="&identity.securityView.label;"
                descriptionheightworkaround="true">
       <vbox class="identity-popup-security-content">
         <label class="plain">
@@ -173,17 +183,17 @@
                 accesskey="&identity.disableMixedContentBlocking.accesskey;"
                 oncommand="gIdentityHandler.disableMixedContentProtection()"/>
         <button when-mixedcontent="active-loaded" class="subviewkeynav"
                 label="&identity.enableMixedContentBlocking.label;"
                 accesskey="&identity.enableMixedContentBlocking.accesskey;"
                 oncommand="gIdentityHandler.enableMixedContentProtection()"/>
       </vbox>
 
-      <vbox id="identity-popup-securityView-footer">
+      <vbox id="identity-popup-more-info-footer" class="identity-popup-footer">
         <!-- More Security Information -->
         <button id="identity-popup-more-info"  class="subviewkeynav"
                 label="&identity.moreInfoLinkText2;"
                 oncommand="gIdentityHandler.handleMoreInfoClick(event);"/>
       </vbox>
 
     </panelview>
   </panelmultiview>

--- a/browser/locales/en-US/chrome/browser/browser.dtd
+++ b/browser/locales/en-US/chrome/browser/browser.dtd
@@ -784,16 +784,18 @@ you can use these alternative items. Oth
 <!ENTITY identity.disableMixedContentBlocking.accesskey "D">
 <!ENTITY identity.learnMore "Learn More">
 
 <!ENTITY identity.removeCertException.label "Remove Exception">
 <!ENTITY identity.removeCertException.accesskey "R">
 
 <!ENTITY identity.moreInfoLinkText2 "More Information">
 
+<!ENTITY identity.clearSiteData "Clear Cookies and Site Data">
+
 <!ENTITY identity.permissions "Permissions">
 <!ENTITY identity.permissionsEmpty "You have not granted this site any special permissions.">
 <!ENTITY identity.permissionsReloadHint "You may need to reload the page for changes to apply.">
 
 <!-- Name for the tabs toolbar as spoken by screen readers.
      The word "toolbar" is appended automatically and should not be contained below! -->
 <!ENTITY tabsToolbar.label "Browser tabs">
 

--- a/browser/themes/shared/controlcenter/panel.inc.css
+++ b/browser/themes/shared/controlcenter/panel.inc.css
@@ -234,37 +234,40 @@
 
 #identity-popup-securityView-body {
   margin-inline-start: calc(2em + 24px);
   margin-inline-end: 1em;
   border-top: 1px solid var(--panel-separator-color);
   padding-inline-end: 1em;
 }
 
-#identity-popup-securityView-footer {
+#identity-popup-more-info-footer {
   margin-top: 1em;
+}
+
+.identity-popup-footer {
   background-color: var(--arrowpanel-dimmed);
 }
 
-#identity-popup-securityView-footer > button {
+.identity-popup-footer > button {
   -moz-appearance: none;
   margin: 0;
   border: none;
   border-top: 1px solid var(--panel-separator-color);
   padding: 8px 20px;
   color: inherit;
   background-color: transparent;
 }
 
-#identity-popup-securityView-footer > button:hover,
-#identity-popup-securityView-footer > button:focus {
+.identity-popup-footer > button:hover,
+.identity-popup-footer > button:focus {
   background-color: var(--arrowpanel-dimmed);
 }
 
-#identity-popup-securityView-footer > button:hover:active {
+.identity-popup-footer > button:hover:active {
   background-color: var(--arrowpanel-dimmed-further);
 }
 
 #identity-popup-content-verifier ~ description {
   margin-top: 1em;
   color: Graytext;
 }