--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -4756,28 +4756,32 @@ nsBrowserAccess.prototype = {
 
     if (aWhere == Ci.nsIBrowserDOMWindow.OPEN_DEFAULTWINDOW) {
       if (isExternal &&
           gPrefService.prefHasUserValue("browser.link.open_newwindow.override.external"))
         aWhere = gPrefService.getIntPref("browser.link.open_newwindow.override.external");
       else
         aWhere = gPrefService.getIntPref("browser.link.open_newwindow");
     }
+    let isPrivate = PrivateBrowsingUtils.isWindowPrivate(aOpener || window);
     switch (aWhere) {
       case Ci.nsIBrowserDOMWindow.OPEN_NEWWINDOW :
         // FIXME: Bug 408379. So how come this doesn't send the
         // referrer like the other loads do?
         var url = aURI ? aURI.spec : "about:blank";
+        let features = "all,dialog=no";
+        if (isPrivate) {
+          features += ",private";
+        }
         // Pass all params to openDialog to ensure that "url" isn't passed through
         // loadOneOrMoreURIs, which splits based on "|"
-        newWindow = openDialog(getBrowserURL(), "_blank", "all,dialog=no", url, null, null, null);
+        newWindow = openDialog(getBrowserURL(), "_blank", features, url, null, null, null);
         break;
       case Ci.nsIBrowserDOMWindow.OPEN_NEWTAB :
         let referrer = aOpener ? makeURI(aOpener.location.href) : null;
-        let isPrivate = PrivateBrowsingUtils.isWindowPrivate(aOpener || window);
         let browser = this._openURIInNewTab(aURI, referrer, isPrivate, isExternal);
         if (browser)
           newWindow = browser.contentWindow;
         break;
       default : // OPEN_CURRENTWINDOW or an illegal value
         newWindow = content;
         if (aURI) {
           let referrer = aOpener ? makeURI(aOpener.location.href) : null;

--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -9630,19 +9630,23 @@ nsDocShell::InternalLoad(nsIURI * aURI,
             nsCOMPtr<nsPIDOMWindow> win = GetWindow();
             NS_ENSURE_TRUE(win, NS_ERROR_NOT_AVAILABLE);
 
             nsDependentString name(aWindowTarget);
             nsCOMPtr<nsIDOMWindow> newWin;
             nsAutoCString spec;
             if (aURI)
                 aURI->GetSpec(spec);
+            nsAutoString features;
+            if (mInPrivateBrowsing) {
+              features.AssignLiteral("private");
+            }
             rv = win->OpenNoNavigate(NS_ConvertUTF8toUTF16(spec),
                                      name,          // window name
-                                     EmptyString(), // Features
+                                     features,
                                      getter_AddRefs(newWin));
 
             // In some cases the Open call doesn't actually result in a new
             // window being opened.  We can detect these cases by examining the
             // document in |newWin|, if any.
             nsCOMPtr<nsPIDOMWindow> piNewWin = do_QueryInterface(newWin);
             if (piNewWin) {
                 nsCOMPtr<nsIDocument> newDoc = piNewWin->GetExtantDoc();