--- a/dom/plugins/base/nsPluginHost.cpp
+++ b/dom/plugins/base/nsPluginHost.cpp
@@ -1813,19 +1813,49 @@ struct CompareFilesByTime
   Equals(const nsCOMPtr<nsIFile>& a, const nsCOMPtr<nsIFile>& b) const
   {
     return GetPluginLastModifiedTime(a) == GetPluginLastModifiedTime(b);
   }
 };
 
 } // anonymous namespace
 
+bool
+nsPluginHost::ShouldAddPlugin(nsPluginTag* aPluginTag)
+{
+#if defined(XP_WIN) && (defined(__x86_64__) || defined(_M_X64))
+  // On 64-bit windows, the only plugin we should load is flash. Use library
+  // filename and MIME type to check.
+  if (StringBeginsWith(aPluginTag->mFileName, NS_LITERAL_CSTRING("NPSWF"), nsCaseInsensitiveCStringComparator()) &&
+      (aPluginTag->HasMimeType(NS_LITERAL_CSTRING("application/x-shockwave-flash")) ||
+       aPluginTag->HasMimeType(NS_LITERAL_CSTRING("application/x-shockwave-flash-test")))) {
+    return true;
+  }
+  // Accept the test plugin MIME types, so mochitests still work.
+  if (aPluginTag->HasMimeType(NS_LITERAL_CSTRING("application/x-test")) ||
+      aPluginTag->HasMimeType(NS_LITERAL_CSTRING("application/x-Second-Test")) ||
+      aPluginTag->HasMimeType(NS_LITERAL_CSTRING("application/x-java-test"))) {
+    return true;
+  }
+#ifdef PLUGIN_LOGGING
+  PLUGIN_LOG(PLUGIN_LOG_NORMAL,
+             ("ShouldAddPlugin : Ignoring non-flash plugin library %s\n", aPluginTag->mFileName.get()));
+#endif // PLUGIN_LOGGING
+  return false;
+#else
+  return true;
+#endif // defined(XP_WIN) && (defined(__x86_64__) || defined(_M_X64))
+}
+
 void
 nsPluginHost::AddPluginTag(nsPluginTag* aPluginTag)
 {
+  if (!ShouldAddPlugin(aPluginTag)) {
+    return;
+  }
   aPluginTag->mNext = mPlugins;
   mPlugins = aPluginTag;
 
   if (aPluginTag->IsActive()) {
     nsAdoptingCString disableFullPage =
       Preferences::GetCString(kPrefDisableFullPage);
     for (uint32_t i = 0; i < aPluginTag->mMimeTypes.Length(); i++) {
       if (!IsTypeInList(aPluginTag->mMimeTypes[i], disableFullPage)) {
@@ -2970,16 +3000,21 @@ nsPluginHost::ReadPluginInfo()
 
     // Import flags from registry into prefs for old registry versions
     if (hasValidFlags && !pluginStateImported) {
       tag->ImportFlagsToPrefs(tagflag);
     }
 
     MOZ_LOG(nsPluginLogging::gPluginLog, PLUGIN_LOG_BASIC,
       ("LoadCachedPluginsInfo : Loading Cached plugininfo for %s\n", tag->mFileName.get()));
+
+    if (!ShouldAddPlugin(tag)) {
+      continue;
+    }
+
     tag->mNext = mCachedPlugins;
     mCachedPlugins = tag;
   }
 
 // On Android we always want to try to load a plugin again (Flash). Bug 935676.
 #ifndef MOZ_WIDGET_ANDROID
   if (hasInvalidPlugins) {
     if (!ReadSectionHeader(reader, "INVALID")) {

--- a/dom/plugins/base/nsPluginHost.h
+++ b/dom/plugins/base/nsPluginHost.h
@@ -328,16 +328,20 @@ private:
   // To be used by the chrome process; returns the current epoch.
   uint32_t ChromeEpoch();
 
   // To be used by the content process to get/set the last observed epoch value
   // from the chrome process.
   uint32_t ChromeEpochForContent();
   void SetChromeEpochForContent(uint32_t aEpoch);
 
+  // On certain platforms, we only want to load certain plugins. This function
+  // centralizes loading rules.
+  bool ShouldAddPlugin(nsPluginTag* aPluginTag);
+
   nsRefPtr<nsPluginTag> mPlugins;
   nsRefPtr<nsPluginTag> mCachedPlugins;
   nsRefPtr<nsInvalidPluginTag> mInvalidPlugins;
   nsTArray< nsRefPtr<nsPluginPlayPreviewInfo> > mPlayPreviewMimeTypes;
   bool mPluginsLoaded;
 
   // set by pref plugin.override_internal_types
   bool mOverrideInternalTypes;