diff --git a/js/public/RootingAPI.h b/js/public/RootingAPI.h
index 99295f123882..67c26f0267e7 100644
--- a/js/public/RootingAPI.h
+++ b/js/public/RootingAPI.h
@@ -856,6 +856,10 @@ class SkipRoot
     void init(js::ContextFriendFields *cx, const T *ptr, size_t count) {}
 
   public:
+    ~SkipRoot() {
+        // An empty destructor is needed to avoid warnings from clang about
+        // unused local variables of this type.
+    }
 
 #endif /* DEBUG && JSGC_ROOT_ANALYSIS */
 
diff --git a/js/src/builtin/BinaryData.cpp b/js/src/builtin/BinaryData.cpp
index f0155af8463c..344b1487fbce 100644
--- a/js/src/builtin/BinaryData.cpp
+++ b/js/src/builtin/BinaryData.cpp
@@ -23,6 +23,8 @@
 #include "jsatominlines.h"
 #include "jsobjinlines.h"
 
+using mozilla::DebugOnly;
+
 using namespace js;
 
 /*
@@ -1552,7 +1554,7 @@ StructType::layout(JSContext *cx, HandleObject structType, HandleObject fields)
 
         // If the field type is a BinaryType and we can't get its bytes, we have a problem.
         RootedValue fieldTypeBytes(cx);
-        bool r = JSObject::getProperty(cx, fieldType, fieldType, cx->names().bytes, &fieldTypeBytes);
+        DebugOnly<bool> r = JSObject::getProperty(cx, fieldType, fieldType, cx->names().bytes, &fieldTypeBytes);
         JS_ASSERT(r);
 
         JS_ASSERT(fieldTypeBytes.isInt32());
diff --git a/js/src/gc/Zone.cpp b/js/src/gc/Zone.cpp
index c3f07e58e725..cc4ca41c80d2 100644
--- a/js/src/gc/Zone.cpp
+++ b/js/src/gc/Zone.cpp
@@ -18,6 +18,8 @@
 
 #include "jsgcinlines.h"
 
+#include "vm/ObjectImpl-inl.h"
+
 using namespace js;
 using namespace js::gc;
 
diff --git a/js/src/ion/shared/CodeGenerator-x86-shared.cpp b/js/src/ion/shared/CodeGenerator-x86-shared.cpp
index 3d65ec41bcdf..5a3fb234164a 100644
--- a/js/src/ion/shared/CodeGenerator-x86-shared.cpp
+++ b/js/src/ion/shared/CodeGenerator-x86-shared.cpp
@@ -376,9 +376,10 @@ CodeGeneratorX86Shared::visitMinMaxD(LMinMaxD *ins)
 {
     FloatRegister first = ToFloatRegister(ins->first());
     FloatRegister second = ToFloatRegister(ins->second());
+#ifdef DEBUG
     FloatRegister output = ToFloatRegister(ins->output());
-
     JS_ASSERT(first == output);
+#endif
 
     Label done, nan, minMaxInst;
 
diff --git a/js/src/jscntxtinlines.h b/js/src/jscntxtinlines.h
index fea20621da6f..b11840b9ca60 100644
--- a/js/src/jscntxtinlines.h
+++ b/js/src/jscntxtinlines.h
@@ -433,6 +433,10 @@ class AutoLockForExclusiveAccess
     AutoLockForExclusiveAccess(JSRuntime *rt MOZ_GUARD_OBJECT_NOTIFIER_PARAM) {
         MOZ_GUARD_OBJECT_NOTIFIER_INIT;
     }
+    ~AutoLockForExclusiveAccess() {
+        // An empty destructor is needed to avoid warnings from clang about
+        // unused local variables of this type.
+    }
 #endif // JS_THREADSAFE
 
     MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
diff --git a/js/src/jsfun.cpp b/js/src/jsfun.cpp
index 2fa56bcd0293..fadc6a622a05 100644
--- a/js/src/jsfun.cpp
+++ b/js/src/jsfun.cpp
@@ -507,7 +507,7 @@ Class JSFunction::class_ = {
     fun_trace
 };
 
-JS_FRIEND_DATA(Class* const) js::FunctionClassPtr = &JSFunction::class_;
+Class* const js::FunctionClassPtr = &JSFunction::class_;
 
 /* Find the body of a function (not including braces). */
 static bool
diff --git a/js/src/jsobj.cpp b/js/src/jsobj.cpp
index 527514296f84..792231fb6e36 100644
--- a/js/src/jsobj.cpp
+++ b/js/src/jsobj.cpp
@@ -80,7 +80,7 @@ Class JSObject::class_ = {
     JS_ConvertStub
 };
 
-JS_FRIEND_DATA(Class* const) js::ObjectClassPtr = &JSObject::class_;
+Class* const js::ObjectClassPtr = &JSObject::class_;
 
 JS_FRIEND_API(JSObject *)
 JS_ObjectToInnerObject(JSContext *cx, JSObject *objArg)
diff --git a/js/src/jsproxy.cpp b/js/src/jsproxy.cpp
index 4101908bbe19..ee1df97431bc 100644
--- a/js/src/jsproxy.cpp
+++ b/js/src/jsproxy.cpp
@@ -3133,7 +3133,7 @@ Class js::ObjectProxyObject::class_ = {
     }
 };
 
-JS_FRIEND_DATA(Class* const) js::ObjectProxyClassPtr = &ObjectProxyObject::class_;
+Class* const js::ObjectProxyClassPtr = &ObjectProxyObject::class_;
 
 Class js::OuterWindowProxyObject::class_ = {
     "Proxy",
@@ -3192,7 +3192,7 @@ Class js::OuterWindowProxyObject::class_ = {
     }
 };
 
-JS_FRIEND_DATA(Class* const) js::OuterWindowProxyClassPtr = &OuterWindowProxyObject::class_;
+Class* const js::OuterWindowProxyClassPtr = &OuterWindowProxyObject::class_;
 
 static bool
 proxy_Call(JSContext *cx, unsigned argc, Value *vp)
@@ -3263,7 +3263,7 @@ Class js::FunctionProxyObject::class_ = {
     }
 };
 
-JS_FRIEND_DATA(Class* const) js::FunctionProxyClassPtr = &FunctionProxyObject::class_;
+Class* const js::FunctionProxyClassPtr = &FunctionProxyObject::class_;
 
 /* static */ ProxyObject *
 ProxyObject::New(JSContext *cx, BaseProxyHandler *handler, HandleValue priv, TaggedProto proto_,
diff --git a/js/src/jsworkers.h b/js/src/jsworkers.h
index fcab0a960898..36dae078f0ee 100644
--- a/js/src/jsworkers.h
+++ b/js/src/jsworkers.h
@@ -289,8 +289,10 @@ class AutoUnlockWorkerThreadState
 /* Pause any threads that are running jobs off thread during GC activity. */
 class AutoPauseWorkersForGC
 {
+#ifdef JS_WORKER_THREADS
     JSRuntime *runtime;
     bool needsUnpause;
+#endif
     MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
 
   public:
diff --git a/js/src/vm/ThreadPool.cpp b/js/src/vm/ThreadPool.cpp
index faeb25e8be45..6f4c522252a9 100644
--- a/js/src/vm/ThreadPool.cpp
+++ b/js/src/vm/ThreadPool.cpp
@@ -186,7 +186,10 @@ ThreadPoolWorker::terminate()
 // them down when requested.
 
 ThreadPool::ThreadPool(JSRuntime *rt)
-  : runtime_(rt),
+  :
+#if defined(JS_THREADSAFE) || defined(DEBUG)
+    runtime_(rt),
+#endif
     numWorkers_(0), // updated during init()
     nextId_(0)
 {
diff --git a/js/src/vm/ThreadPool.h b/js/src/vm/ThreadPool.h
index eb5ff8467185..8e7f34838ace 100644
--- a/js/src/vm/ThreadPool.h
+++ b/js/src/vm/ThreadPool.h
@@ -70,7 +70,9 @@ class ThreadPool
     friend class ThreadPoolWorker;
 
     // Initialized at startup only:
+#if defined(JS_THREADSAFE) || defined(DEBUG)
     JSRuntime *const runtime_;
+#endif
     js::Vector<ThreadPoolWorker*, 8, SystemAllocPolicy> workers_;
 
     // Number of workers we will start, when we actually start them