diff --git a/dom/base/nsObjectLoadingContent.cpp b/dom/base/nsObjectLoadingContent.cpp
index e5ea23ef89225..48fdfd9510825 100644
--- a/dom/base/nsObjectLoadingContent.cpp
+++ b/dom/base/nsObjectLoadingContent.cpp
@@ -110,6 +110,7 @@ static const char *kPrefJavaMIME = "plugin.java.mime";
 static const char *kPrefYoutubeRewrite = "plugins.rewrite_youtube_embeds";
 static const char *kPrefBlockURIs = "browser.safebrowsing.blockedURIs.enabled";
 static const char *kPrefFavorFallbackMode = "plugins.favorfallback.mode";
+static const char *kPrefFavorFallbackRules = "plugins.favorfallback.rules";
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -3452,7 +3453,89 @@ nsObjectLoadingContent::HasGoodFallback() {
     return false;
   }
 
-  // xxx to be filled
+  nsTArray<nsCString> rulesList;
+  nsCString prefString;
+  if (NS_SUCCEEDED(Preferences::GetCString(kPrefFavorFallbackRules, &prefString))) {
+      ParseString(prefString, ',', rulesList);
+  }
+
+  for (uint32_t i = 0; i < rulesList.Length(); ++i) {
+    // RULE "embed":
+    // Don't use fallback content if the object contains an <embed> inside its
+    // fallback content.
+    if (rulesList[i].EqualsLiteral("embed")) {
+      nsTArray<nsINodeList*> childNodes;
+      for (nsIContent* child = thisContent->GetFirstChild();
+           child;
+           child = child->GetNextNode(thisContent)) {
+        if (child->IsHTMLElement(nsGkAtoms::embed)) {
+          return false;
+        }
+      }
+    }
+
+    // RULE "video":
+    // Use fallback content if the object contains a <video> inside its
+    // fallback content.
+    if (rulesList[i].EqualsLiteral("video")) {
+      nsTArray<nsINodeList*> childNodes;
+      for (nsIContent* child = thisContent->GetFirstChild();
+           child;
+           child = child->GetNextNode(thisContent)) {
+        if (child->IsHTMLElement(nsGkAtoms::video)) {
+          return true;
+        }
+      }
+    }
+
+    // RULE "adobelink":
+    // Don't use fallback content when it has a link to adobe's website.
+    if (rulesList[i].EqualsLiteral("adobelink")) {
+      nsTArray<nsINodeList*> childNodes;
+      for (nsIContent* child = thisContent->GetFirstChild();
+           child;
+           child = child->GetNextNode(thisContent)) {
+        if (child->IsHTMLElement(nsGkAtoms::a)) {
+          nsCOMPtr<nsIURI> href = child->GetHrefURI();
+          if (href) {
+            nsAutoCString asciiHost;
+            nsresult rv = href->GetAsciiHost(asciiHost);
+            if (NS_SUCCEEDED(rv) &&
+                !asciiHost.IsEmpty() &&
+                (asciiHost.EqualsLiteral("adobe.com") ||
+                 StringEndsWith(asciiHost, NS_LITERAL_CSTRING(".adobe.com")))) {
+              return false;
+            }
+          }
+        }
+      }
+    }
+
+    // RULE "installinstructions":
+    // Don't use fallback content when the text content on the fallback appears
+    // to contain instructions to install or download Flash.
+    if (rulesList[i].EqualsLiteral("installinstructions")) {
+      nsAutoString textContent;
+      ErrorResult rv;
+      thisContent->GetTextContent(textContent, rv);
+      bool hasText =
+        !rv.Failed() &&
+        (CaseInsensitiveFindInReadable(NS_LITERAL_STRING("Flash"), textContent) ||
+         CaseInsensitiveFindInReadable(NS_LITERAL_STRING("Install"), textContent) ||
+         CaseInsensitiveFindInReadable(NS_LITERAL_STRING("Download"), textContent));
+
+      if (hasText) {
+        return false;
+      }
+    }
+
+    // RULE "true":
+    // By having a rule that returns true, we can put it at the end of the rules list
+    // to change the default-to-false behavior to be default-to-true.
+    if (rulesList[i].EqualsLiteral("true")) {
+      return true;
+    }
+  }
 
   return false;
 }
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 4caea9587e40b..66aeb37c669bc 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -2832,6 +2832,12 @@ pref("plugin.persistentPermissionAlways.intervalInDays", 90);
 // "never"      - never use favor fallback mode
 pref("plugins.favorfallback.mode", "never");
 
+// A comma-separated list of rules to follow when deciding
+// whether an object has been provided with good fallback content.
+// The valid values can be found at nsObjectLoadingContent::HasGoodFallback.
+pref("plugins.favorfallback.rules", "");
+
+
 // Set IPC timeouts for plugins and tabs, except in leak-checking and
 // dynamic analysis builds.  (NS_FREE_PERMANENT_DATA is C++ only, so
 // approximate its definition here.)