diff --git a/js/xpconnect/loader/mozJSComponentLoader.cpp b/js/xpconnect/loader/mozJSComponentLoader.cpp
index 6caea850dae7..477445bbe382 100644
--- a/js/xpconnect/loader/mozJSComponentLoader.cpp
+++ b/js/xpconnect/loader/mozJSComponentLoader.cpp
@@ -457,7 +457,7 @@ mozJSComponentLoader::FindTargetObject(JSContext* aCx,
     if (mReuseLoaderGlobal) {
         JSFunction *fun = js::GetOutermostEnclosingFunctionOfScriptedCaller(aCx);
         if (fun) {
-            JSObject *funParent = js::GetObjectParent(JS_GetFunctionObject(fun));
+            JSObject *funParent = js::GetObjectEnvironmentObjectForFunction(fun);
             if (JS_GetClass(funParent) == &kFakeBackstagePassJSClass)
                 targetObject = funParent;
         }
@@ -783,9 +783,14 @@ mozJSComponentLoader::ObjectForLocation(ComponentLoaderInfo &aInfo,
             if (!mReuseLoaderGlobal) {
                 Compile(cx, obj, options, buf, fileSize32, &script);
             } else {
-                CompileFunction(cx, obj, options,
-                                nullptr, 0, nullptr,
-                                buf, fileSize32, &function);
+                // Note: exceptions will get handled further down;
+                // don't early return for them here.
+                AutoObjectVector scopeChain(cx);
+                if (scopeChain.append(obj)) {
+                    CompileFunction(cx, scopeChain,
+                                    options, nullptr, 0, nullptr,
+                                    buf, fileSize32, &function);
+                }
             }
 
             PR_MemUnmap(buf, fileSize32);
@@ -829,9 +834,14 @@ mozJSComponentLoader::ObjectForLocation(ComponentLoaderInfo &aInfo,
                 script = Compile(cx, obj, options, buf,
                                      fileSize32);
             } else {
-                function = CompileFunction(cx, obj, options,
-                                           nullptr, 0, nullptr,
-                                           buf, fileSize32);
+                // Note: exceptions will get handled further down;
+                // don't early return for them here.
+                AutoObjectVector scopeChain(cx);
+                if (scopeChain.append(obj)) {
+                    CompileFunction(cx, scopeChain,
+                                    options, nullptr, 0, nullptr,
+                                    buf, fileSize32, &function);
+                }
             }
 
             free(buf);
@@ -869,9 +879,14 @@ mozJSComponentLoader::ObjectForLocation(ComponentLoaderInfo &aInfo,
             if (!mReuseLoaderGlobal) {
                 Compile(cx, obj, options, buf, bytesRead, &script);
             } else {
-                CompileFunction(cx, obj, options,
-                                nullptr, 0, nullptr,
-                                buf, bytesRead, &function);
+                // Note: exceptions will get handled further down;
+                // don't early return for them here.
+                AutoObjectVector scopeChain(cx);
+                if (scopeChain.append(obj)) {
+                    CompileFunction(cx, scopeChain,
+                                    options, nullptr, 0, nullptr,
+                                    buf, bytesRead, &function);
+                }
             }
         }
         // Propagate the exception, if one exists. Also, don't leave the stale
diff --git a/js/xpconnect/loader/mozJSSubScriptLoader.cpp b/js/xpconnect/loader/mozJSSubScriptLoader.cpp
index 2ec843d450ab..3b2d13b45f0c 100644
--- a/js/xpconnect/loader/mozJSSubScriptLoader.cpp
+++ b/js/xpconnect/loader/mozJSSubScriptLoader.cpp
@@ -90,6 +90,22 @@ ReportError(JSContext *cx, const char *msg)
     return NS_OK;
 }
 
+// There probably aren't actually any consumers that rely on having the full
+// scope chain up the parent chain of "obj" (instead of just having obj and then
+// the global), but we do this for now to preserve backwards compat.
+static bool
+BuildScopeChainForObject(JSContext *cx, HandleObject obj,
+                         AutoObjectVector &scopeChain)
+{
+    RootedObject cur(cx, obj);
+    for ( ; cur && !JS_IsGlobalObject(cur); cur = JS_GetParent(cur)) {
+        if (!scopeChain.append(cur)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 nsresult
 mozJSSubScriptLoader::ReadScript(nsIURI *uri, JSContext *cx, JSObject *targetObjArg,
                                  const nsAString &charset, const char *uriStr,
@@ -161,10 +177,13 @@ mozJSSubScriptLoader::ReadScript(nsIURI *uri, JSContext *cx, JSObject *targetObj
         if (!reuseGlobal) {
             JS::Compile(cx, target_obj, options, srcBuf, script);
         } else {
-            JS::CompileFunction(cx, target_obj, options,
-                                nullptr, 0, nullptr,
-                                srcBuf,
-                                function);
+            AutoObjectVector scopeChain(cx);
+            if (!BuildScopeChainForObject(cx, target_obj, scopeChain)) {
+                return NS_ERROR_OUT_OF_MEMORY;
+            }
+            // XXXbz do we really not care if the compile fails???
+            JS::CompileFunction(cx, scopeChain, options, nullptr, 0, nullptr,
+                                srcBuf, function);
         }
     } else {
         // We only use lazy source when no special encoding is specified because
@@ -173,9 +192,13 @@ mozJSSubScriptLoader::ReadScript(nsIURI *uri, JSContext *cx, JSObject *targetObj
             options.setSourceIsLazy(true);
             JS::Compile(cx, target_obj, options, buf.get(), len, script);
         } else {
-            JS::CompileFunction(cx, target_obj, options,
-                                nullptr, 0, nullptr, buf.get(),
-                                len, function);
+            AutoObjectVector scopeChain(cx);
+            if (!BuildScopeChainForObject(cx, target_obj, scopeChain)) {
+                return NS_ERROR_OUT_OF_MEMORY;
+            }
+            // XXXbz do we really not care if the compile fails???
+            JS::CompileFunction(cx, scopeChain, options, nullptr, 0, nullptr,
+                                buf.get(), len, function);
         }
     }