--- a/toolkit/components/passwordmgr/nsLoginManagerPrompter.js
+++ b/toolkit/components/passwordmgr/nsLoginManagerPrompter.js
@@ -83,16 +83,20 @@ LoginManagerPromptFactory.prototype = {
     }
 
     // If login manger has logins for this host, defer prompting if we're
     // already waiting on a master password entry.
     var prompt = this._asyncPrompts[hashKey];
     var prompter = prompt.prompter;
     var [hostname, httpRealm] = prompter._getAuthTarget(prompt.channel, prompt.authInfo);
     var hasLogins = (prompter._pwmgr.countLogins(hostname, null, httpRealm) > 0);
+    if (!hasLogins && LoginHelper.schemeUpgrades && hostname.startsWith("https://")) {
+      let httpHostname = hostname.replace(/^https:\/\//, "http://");
+      hasLogins = (prompter._pwmgr.countLogins(httpHostname, null, httpRealm) > 0);
+    }
     if (hasLogins && prompter._pwmgr.uiBusy) {
       this.log("_doAsyncPrompt:run bypassed, master password UI busy");
       return;
     }
 
     this._asyncPromptInProgress = true;
     prompt.inProgress = true;
 
@@ -506,31 +510,41 @@ LoginManagerPrompter.prototype = {
    */
   promptAuth : function (aChannel, aLevel, aAuthInfo) {
     var selectedLogin = null;
     var checkbox = { value : false };
     var checkboxLabel = null;
     var epicfail = false;
     var canAutologin = false;
     var notifyObj;
+    var foundLogins;
 
     try {
       this.log("===== promptAuth called =====");
 
       // If the user submits a login but it fails, we need to remove the
       // notification bar that was displayed. Conveniently, the user will
       // be prompted for authentication again, which brings us here.
       this._removeLoginNotifications();
 
       var [hostname, httpRealm] = this._getAuthTarget(aChannel, aAuthInfo);
 
       // Looks for existing logins to prefill the prompt with.
-      var foundLogins = this._pwmgr.findLogins({},
-                                               hostname, null, httpRealm);
-      this.log("found " + foundLogins.length + " matching logins.");
+      foundLogins = LoginHelper.searchLoginsWithObject({
+        hostname,
+        httpRealm,
+        schemeUpgrades: LoginHelper.schemeUpgrades,
+      });
+      this.log("found", foundLogins.length, "matching logins.");
+      let resolveBy = [
+        "scheme",
+        "timePasswordChanged",
+      ];
+      foundLogins = LoginHelper.dedupeLogins(foundLogins, ["username"], resolveBy, hostname);
+      this.log(foundLogins.length, "matching logins remain after deduping");
 
       // XXX Can't select from multiple accounts yet. (bug 227632)
       if (foundLogins.length > 0) {
         selectedLogin = foundLogins[0];
         this._SetAuthInfo(aAuthInfo, selectedLogin.username,
                                      selectedLogin.password);
 
         // Allow automatic proxy login