--- a/dom/security/nsCSPParser.cpp
+++ b/dom/security/nsCSPParser.cpp
@@ -1,15 +1,16 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/ArrayUtils.h"
+#include "mozilla/Preferences.h"
 #include "nsCOMPtr.h"
 #include "nsCSPParser.h"
 #include "nsCSPUtils.h"
 #include "nsIConsoleService.h"
 #include "nsIContentPolicy.h"
 #include "nsIScriptError.h"
 #include "nsIStringBundle.h"
 #include "nsNetUtil.h"
@@ -115,16 +116,17 @@ nsCSPTokenizer::tokenizeCSPPolicy(const 
 
   nsCSPTokenizer tokenizer(aPolicyString.BeginReading(),
                            aPolicyString.EndReading());
 
   tokenizer.generateTokens(outTokens);
 }
 
 /* ===== nsCSPParser ==================== */
+bool nsCSPParser::sCSPExperimentalEnabled = false;
 
 nsCSPParser::nsCSPParser(cspTokens& aTokens,
                          nsIURI* aSelfURI,
                          nsCSPContext* aCSPContext,
                          bool aDeliveredViaMetaTag)
  : mCurChar(nullptr)
  , mEndChar(nullptr)
  , mHasHashOrNonce(false)
@@ -132,16 +134,21 @@ nsCSPParser::nsCSPParser(cspTokens& aTok
  , mChildSrc(nullptr)
  , mFrameSrc(nullptr)
  , mTokens(aTokens)
  , mSelfURI(aSelfURI)
  , mPolicy(nullptr)
  , mCSPContext(aCSPContext)
  , mDeliveredViaMetaTag(aDeliveredViaMetaTag)
 {
+  static bool initialized = false;
+  if (!initialized) {
+    initialized = true;
+    Preferences::AddBoolVarCache(&sCSPExperimentalEnabled, "security.csp.experimentalEnabled");
+  }
   CSPPARSERLOG(("nsCSPParser::nsCSPParser"));
 }
 
 nsCSPParser::~nsCSPParser()
 {
   CSPPARSERLOG(("nsCSPParser::~nsCSPParser"));
 }
 
@@ -1002,37 +1009,32 @@ nsCSPParser::directiveValue(nsTArray<nsC
 
   // special case handling of the referrer directive (since it doesn't contain
   // source lists)
   if (CSP_IsDirective(mCurDir[0], nsIContentSecurityPolicy::REFERRER_DIRECTIVE)) {
     referrerDirectiveValue();
     return;
   }
 
-  // special case handling of the require-sri-for directive (since it doesn't
-  // contain a source lists but rather types, e.g., style or script)
-  if (CSP_IsDirective(mCurDir[0], nsIContentSecurityPolicy::REQUIRE_SRI_FOR)) {
-    // handled in directive()
-    return;
-  }
-
   // Otherwise just forward to sourceList
   sourceList(outSrcs);
 }
 
 // directive-name = 1*( ALPHA / DIGIT / "-" )
 nsCSPDirective*
 nsCSPParser::directiveName()
 {
   CSPPARSERLOG(("nsCSPParser::directiveName, mCurToken: %s, mCurValue: %s",
                NS_ConvertUTF16toUTF8(mCurToken).get(),
                NS_ConvertUTF16toUTF8(mCurValue).get()));
 
   // Check if it is a valid directive
-  if (!CSP_IsValidDirective(mCurToken)) {
+  if (!CSP_IsValidDirective(mCurToken) ||
+       (!sCSPExperimentalEnabled &&
+         CSP_IsDirective(mCurToken, nsIContentSecurityPolicy::REQUIRE_SRI_FOR))) {
     const char16_t* params[] = { mCurToken.get() };
     logWarningErrorToConsole(nsIScriptError::warningFlag, "couldNotProcessUnknownDirective",
                              params, ArrayLength(params));
     return nullptr;
   }
 
   // The directive 'reflected-xss' is part of CSP 1.1, see:
   // http://www.w3.org/TR/2014/WD-CSP11-20140211/#reflected-xss

--- a/dom/security/nsCSPParser.h
+++ b/dom/security/nsCSPParser.h
@@ -106,16 +106,18 @@ class nsCSPParser {
                                                    bool aDeliveredViaMetaTag);
 
   private:
     nsCSPParser(cspTokens& aTokens,
                 nsIURI* aSelfURI,
                 nsCSPContext* aCSPContext,
                 bool aDeliveredViaMetaTag);
 
+    static bool sCSPExperimentalEnabled;
+
     ~nsCSPParser();
 
 
     // Parsing the CSP using the source-list from http://www.w3.org/TR/CSP11/#source-list
     nsCSPPolicy*        policy();
     void                directive();
     nsCSPDirective*     directiveName();
     void                directiveValue(nsTArray<nsCSPBaseSrc*>& outSrcs);

--- a/dom/security/test/TestCSPParser.cpp
+++ b/dom/security/test/TestCSPParser.cpp
@@ -23,16 +23,18 @@ class nsXPIDLString;
 template<class T> class nsReadingIterator;
 #endif
 
 #include "nsIContentSecurityPolicy.h"
 #include "nsNetUtil.h"
 #include "TestHarness.h"
 #include "nsIScriptSecurityManager.h"
 #include "mozilla/dom/nsCSPContext.h"
+#include "nsIPrefService.h"
+#include "nsIPrefBranch.h"
 
 #ifndef MOZILLA_INTERNAL_API
 #undef nsString_h___
 #undef nsAString_h___
 #undef nsReadableUtils_h___
 #endif
 
 /*
@@ -161,20 +163,33 @@ nsresult runTest(uint32_t aExpectedPolic
 }
 
 // ============================= run Tests ========================
 
 nsresult runTestSuite(const PolicyTest* aPolicies,
                       uint32_t aPolicyCount,
                       uint32_t aExpectedPolicyCount) {
   nsresult rv;
+  nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+  bool experimentalEnabledCache = false;
+  if (prefs)
+  {
+    prefs->GetBoolPref("security.csp.experimentalEnabled", &experimentalEnabledCache);
+    prefs->SetBoolPref("security.csp.experimentalEnabled", true);
+  }
+
   for (uint32_t i = 0; i < aPolicyCount; i++) {
     rv = runTest(aExpectedPolicyCount, aPolicies[i].policy, aPolicies[i].expectedResult);
     NS_ENSURE_SUCCESS(rv, rv);
   }
+
+  if (prefs) {
+    prefs->SetBoolPref("security.csp.experimentalEnabled", experimentalEnabledCache);
+  }
+
   return NS_OK;
 }
 
 // ============================= TestDirectives ========================
 
 nsresult TestDirectives() {
 
   static const PolicyTest policies[] =

--- a/dom/security/test/sri/mochitest.ini
+++ b/dom/security/test/sri/mochitest.ini
@@ -32,8 +32,9 @@ support-files =
   style_301.css^headers^
 
 [test_script_sameorigin.html]
 [test_script_crossdomain.html]
 [test_sri_disabled.html]
 [test_style_crossdomain.html]
 [test_style_sameorigin.html]
 [test_require-sri-for_csp_directive.html]
+[test_require-sri-for_csp_directive_disabled.html]

--- a/dom/security/test/sri/test_require-sri-for_csp_directive.html
+++ b/dom/security/test/sri/test_require-sri-for_csp_directive.html
@@ -9,36 +9,38 @@
   <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
 </head>
 <body>
 <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1265318">Mozilla Bug 1265318</a>
 <iframe style="width:200px;height:200px;" id="test_frame"></iframe>
 </body>
 <script type="application/javascript">
+  SpecialPowers.setBoolPref("security.csp.experimentalEnabled", true);
   SimpleTest.waitForExplicitFinish();
   function handler(event) {
     switch (event.data) {
       case 'good_sriLoaded':
         ok(true, "Eligible SRI resources was correctly loaded.");
         break;
       case 'bad_nonsriLoaded':
         ok(false, "Eligible non-SRI resource should be blocked by the CSP!");
         break;
       case 'good_nonsriBlocked':
         ok(true, "Eligible non-SRI resources was correctly blocked by the CSP.");
         break;
       case 'finish':
         var blackText = frame.contentDocument.getElementById('black-text');
         var blackTextColor = frame.contentWindow.getComputedStyle(blackText, null).getPropertyValue('color');
-        ok(blackTextColor == 'rgb(0, 0, 0)', "The second part should still be black.");
+        ok(blackTextColor == 'rgb(0, 0, 0)', "The second part should not be black.");
         removeEventListener('message', handler);
         SimpleTest.finish();
         break;
       default:
+        ok(false, 'Something is wrong here');
         break;
     }
   }
   addEventListener("message", handler);
   var frame = document.getElementById("test_frame");
   frame.src = "iframe_require-sri-for_main.html";
 </script>
 </html>

new file mode 100644
--- /dev/null
+++ b/dom/security/test/sri/test_require-sri-for_csp_directive_disabled.html
@@ -0,0 +1,46 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for diabled SRI require-sri-for CSP directive</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1265318">Mozilla Bug 1265318</a>
+<iframe style="width:200px;height:200px;" id="test_frame"></iframe>
+</body>
+<script type="application/javascript">
+  SpecialPowers.setBoolPref("security.csp.experimentalEnabled", false);
+  SimpleTest.waitForExplicitFinish();
+  function handler(event) {
+    switch (event.data) {
+      case 'good_sriLoaded':
+        ok(true, "Eligible SRI resources was correctly loaded.");
+        break;
+      case 'bad_nonsriLoaded':
+        ok(true, "Eligible non-SRI resource should be blocked by the CSP!");
+        break;
+      case 'good_nonsriBlocked':
+        ok(false, "Eligible non-SRI resources was correctly blocked by the CSP.");
+        break;
+      case 'finish':
+        var blackText = frame.contentDocument.getElementById('black-text');
+        var blackTextColor = frame.contentWindow.getComputedStyle(blackText, null).getPropertyValue('color');
+        ok(blackTextColor != 'rgb(0, 0, 0)', "The second part should still be black.");
+        removeEventListener('message', handler);
+        SimpleTest.finish();
+        break;
+      default:
+        ok(false, 'Something is wrong here');
+        break;
+    }
+  }
+  addEventListener("message", handler);
+  var frame = document.getElementById("test_frame");
+  frame.src = "iframe_require-sri-for_main.html";
+</script>
+</html>