diff --git a/ANNOUNCE b/ANNOUNCE
index 6dfdef21..1c523009 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -43,6 +43,13 @@ Highlights of this release include:
   requirements, which should fix issues relating to using vector types in
   Objective-C objects.
 
+- The option to build a separate libobjcxx has been removed.  The runtime will
+  now depend on the C++ standard library implementation if no useable C++
+  runtime is available.  Note that C++ exception interworking does not work
+  because LLVM's libc++abi (shipped by Apple) does not provide GNU-compatible
+  hooks and so Objective-C++ exception support will be automatically disabled
+  on this platform.  Any other platforms shipping libc++abi should consider
+  either GNU libsupc++ or libcxxrt as an alternative.
 
 You may obtain the code for this release from git and use the 1.x branch:
 
diff --git a/CMake/CMakeLists.txt b/CMake/CMakeLists.txt
index 9cbdd09b..cdbc20f4 100644
--- a/CMake/CMakeLists.txt
+++ b/CMake/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.1)
 
 add_executable(test_cxx_runtime typeinfo_test.cc)
 set(CMAKE_CXX_IMPLICIT_LINK_LIBRARIES "")
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 26be035c..a0ace72f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,10 @@
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.1)
 
 project(libobjc)
 enable_language(ASM)
 
+INCLUDE (CheckCXXSourceCompiles)
+
 macro(install_symlink filepath sympath)
 	install(CODE "execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink ${filepath} ${sympath})")
 	install(CODE "message(\"-- Symlinking: ${sympath} -> ${filepath}\")")
@@ -364,3 +366,17 @@ if (TESTS)
 	add_subdirectory(Test)
 endif (TESTS)
 
+CHECK_CXX_SOURCE_COMPILES("
+	#include <stdlib.h>
+	extern \"C\" {
+	__attribute__((weak))
+	void *__cxa_allocate_exception(size_t thrown_size) noexcept;
+	}
+	#include <exception>
+	int main() { return 0; }" CXA_ALLOCATE_EXCEPTION_NOEXCEPT_COMPILES)
+
+if (CXA_ALLOCATE_EXCEPTION_NOEXCEPT_COMPILES)
+	add_definitions(-DCXA_ALLOCATE_EXCEPTION_SPECIFIER=noexcept)
+else ()
+	add_definitions(-DCXA_ALLOCATE_EXCEPTION_SPECIFIER=)
+endif ()
diff --git a/Test/AssociatedObject.m b/Test/AssociatedObject.m
index cd9464ea..f3a50e1d 100644
--- a/Test/AssociatedObject.m
+++ b/Test/AssociatedObject.m
@@ -1,4 +1,6 @@
 #include "Test.h"
+#include <stdio.h>
+#include <inttypes.h>
 
 static BOOL deallocCalled = NO;
 static const char* objc_setAssociatedObjectKey = "objc_setAssociatedObjectKey";
@@ -19,8 +21,41 @@ int main(void)
 	@autoreleasepool {
 		Associated *object = [Associated new];
 		Test *holder = [[Test new] autorelease];
-		objc_setAssociatedObject(object, &objc_setAssociatedObjectKey, holder, OBJC_ASSOCIATION_RETAIN);
+		objc_setAssociatedObject(holder, &objc_setAssociatedObjectKey, object, OBJC_ASSOCIATION_RETAIN);
 		[object release];
-    }
+		assert(!deallocCalled);
+	}
+	// dealloc should be called when holder is released during pool drain
 	assert(deallocCalled);
+
+	deallocCalled = NO;
+
+	Associated *object = [Associated new];
+	Test *holder = [Test new];
+	objc_setAssociatedObject(holder, &objc_setAssociatedObjectKey, object, OBJC_ASSOCIATION_RETAIN);
+	[object release]; // commuted into associated object storage
+	objc_setAssociatedObject(holder, &objc_setAssociatedObjectKey, nil, OBJC_ASSOCIATION_ASSIGN);
+	[holder release];
+
+	assert(deallocCalled);
+
+	object = [Associated new];
+	holder = [Test new];
+	for (uintptr_t i = 1; i <= 20; ++i)
+	{
+		objc_setAssociatedObject(holder, (void*)i, object, OBJC_ASSOCIATION_RETAIN);
+	}
+	int lost = 0;
+	for (uintptr_t i = 1; i <= 20; ++i)
+	{
+		if (object != objc_getAssociatedObject(holder, (void*)i))
+		{
+			fprintf(stderr, "lost object %" PRIuPTR "\n", i);
+			++lost;
+		}
+	}
+	[holder release];
+	[object release];
+	assert(0 == lost);
+	return 0;
 }
diff --git a/Test/CMakeLists.txt b/Test/CMakeLists.txt
index 5a19051e..6658e82e 100644
--- a/Test/CMakeLists.txt
+++ b/Test/CMakeLists.txt
@@ -38,6 +38,8 @@ set(TESTS
 	MethodArguments.m
 	zeroSizedIVar.m
 	exchange.m
+	hash_table_delete.c
+	setSuperclass.m
 )
 
 # List of single-file tests that won't work with the legacy ABI and so
diff --git a/Test/hash_table_delete.c b/Test/hash_table_delete.c
new file mode 100644
index 00000000..ad7af896
--- /dev/null
+++ b/Test/hash_table_delete.c
@@ -0,0 +1,64 @@
+#include <stdbool.h>
+#include <stdint.h>
+
+struct test_struct {
+	uintptr_t key;
+};
+
+struct test_struct null_placeholder = {0};
+
+static int test_compare(const void *key, const struct test_struct test) {
+	return (uintptr_t)key == test.key;
+}
+
+// force hash collisions
+static uint32_t test_key_hash(const void *ptr) {
+	return ((uint32_t)(uintptr_t)ptr)>>2;
+}
+
+static uint32_t test_value_hash(const struct test_struct test) {
+	return test.key>>2;
+}
+
+static int test_is_null(const struct test_struct test) {
+	return test.key == 0;
+}
+
+#define MAP_TABLE_NAME test
+#define MAP_TABLE_COMPARE_FUNCTION test_compare
+#define MAP_TABLE_VALUE_TYPE struct test_struct
+#define MAP_TABLE_VALUE_NULL test_is_null
+#define MAP_TABLE_HASH_KEY test_key_hash
+#define MAP_TABLE_HASH_VALUE test_value_hash
+#define MAP_TABLE_VALUE_PLACEHOLDER null_placeholder
+#define MAP_TABLE_ACCESS_BY_REFERENCE 1
+#define MAP_TABLE_SINGLE_THREAD 1
+#define MAP_TABLE_NO_LOCK 1
+
+#include "../hash_table.h"
+
+int main(int argc, char *argv[])
+{
+	test_table *testTable;
+	test_initialize(&testTable, 128);
+
+	struct test_struct one, two, three;
+	one.key = 1;
+	two.key = 2;
+	three.key = 3;
+
+	test_insert(testTable, one);
+	test_insert(testTable, two);
+	test_insert(testTable, three);
+
+	test_remove(testTable, (void*)2);
+	test_remove(testTable, (void*)1);
+
+	struct test_struct *pthree = test_table_get(testTable, (void*)3);
+	if (!pthree) {
+		fprintf(stderr, "failed to find value (key=3) inserted into hash table\n");
+		return 1;
+	}
+
+	return 0;
+}
diff --git a/Test/setSuperclass.m b/Test/setSuperclass.m
new file mode 100644
index 00000000..3ff468b1
--- /dev/null
+++ b/Test/setSuperclass.m
@@ -0,0 +1,297 @@
+#include "../objc/runtime.h"
+#include <assert.h>
+#include <stdio.h>
+
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+
+__attribute__((objc_root_class))
+@interface Root
+{
+	id isa;
+}
+@end
+@interface DefaultSuperclass: Root @end
+
+// test: new superclass when not initialized at the time of class_setSuperclass
+@interface NotInitializedSuperclass1: Root @end
+@interface Subclass1: DefaultSuperclass @end
+
+// test: new superclass when already initialized at the time of class_setSuperclass
+@interface NotInitializedSuperclass2: Root @end
+@interface Subclass2: DefaultSuperclass @end
+@interface Subclass2Subclass: Subclass2 @end
+
+@interface ChangesDuringInitialize: DefaultSuperclass @end
+
+// test: class gets reparented under its parent's parent.
+@interface RemovedFromHierarchy: DefaultSuperclass @end
+@interface MovesUpwardsInHierarchy: RemovedFromHierarchy @end
+
+// test: one class initializes anotherwhile initializing during class_setSuperclass
+@interface OtherInitializedClass: Root @end
+@interface InitializesOneClassWhileBeingInitialized: NotInitializedSuperclass2 @end
+@interface Subclass3: DefaultSuperclass @end
+
+@implementation Root
++ (Class)class { return self; }
++ (BOOL)respondsToSelector:(SEL)selector {
+	return class_respondsToSelector(object_getClass(self), selector);
+}
++ (BOOL)instancesRespondToSelector:(SEL)selector {
+	return class_respondsToSelector(self, selector);
+}
+@end
+
+@implementation NotInitializedSuperclass1
+static BOOL _notInitializedSuperclass1Initialized = NO;
++ (void)initialize {
+	_notInitializedSuperclass1Initialized = YES;
+}
++ (void)existsOnNotInitializedSuperclassMeta { };
++ (int)sameNameMeta { return 12; }
++ (int)overriddenMeta { return 12; }
+
+- (BOOL)existsOnNotInitializedSuperclass { return YES; }
+- (int)sameName { return 2; }
+- (int)overridden { return 2; }
+@end
+
+@implementation NotInitializedSuperclass2
+static BOOL _notInitializedSuperclass2Initialized = NO;
++ (void)initialize {
+	_notInitializedSuperclass2Initialized = YES;
+}
++ (void)existsOnNotInitializedSuperclassMeta { };
++ (int)sameNameMeta { return 13; }
++ (int)overriddenMeta { return 13; }
+- (BOOL)existsOnNotInitializedSuperclass { return YES; }
+- (int)sameName { return 3; }
+- (int)overridden { return 3; }
+@end
+
+@implementation DefaultSuperclass
+static BOOL _alreadyInitializedSuperclassInitialized = NO;
++ (void)initialize {
+	_alreadyInitializedSuperclassInitialized = YES;
+}
++ (void)existsOnDefaultSuperclassMeta { };
++ (int)sameNameMeta { return 14; }
++ (int)overriddenMeta { return 14; }
+- (BOOL)existsOnDefaultSuperclass { return YES; }
+- (int)sameName { return 4; }
+- (int)overridden { return 4; }
+@end
+
+@implementation Subclass1
+static BOOL _subclass1Initialized = NO;
++ (void)initialize {
+	_subclass1Initialized = YES;
+}
++ (int)overriddenMeta { return 15; } // shadows 14
+- (BOOL)existsOnSubclass1 { return YES; }
+- (int)overridden { return 5; } // shadows 4
+@end
+
+@implementation Subclass2
+static BOOL _subclass2Initialized = NO;
++ (void)initialize {
+	_subclass2Initialized = YES;
+}
++ (int)overriddenMeta { return 16; } // shadows 14
+- (BOOL)existsOnSubclass2 { return YES; }
+- (int)overridden { return 6; } // shadows 4
+- (int)intermediateOverride { return 100; }
+@end
+
+@implementation Subclass2Subclass
+- (int)intermediateOverride { return 200; }
+@end
+
+@implementation ChangesDuringInitialize
++ (void)initialize {
+	class_setSuperclass(self, objc_getClass("NotInitializedSuperclass1"));
+}
++ (int)overriddenMeta { return 18; }
+@end
+
+@implementation RemovedFromHierarchy
++ (int)overriddenMeta { return 19; } // shadows 14 on DefaultSuperClass
++ (int)sameNameMeta { return 19; } // shadows 14 on DefaultSuperClass
++ (void)onlyExistsOnRemovedClassMeta { }
+- (void)onlyExistsOnRemovedClass { }
+@end
+
+@implementation MovesUpwardsInHierarchy
++ (int)overriddenMeta { return 20; } // shadows 19 on RemovedFromHierarchy or 14 on DefaultSuperClass
+@end
+
+@implementation OtherInitializedClass
+static BOOL _otherInitializedClassInitialized = NO;
++ (void)initialize {
+	_otherInitializedClassInitialized = YES;
+}
+@end
+
+@implementation InitializesOneClassWhileBeingInitialized
++ (void)initialize {
+	[OtherInitializedClass class];
+}
+@end
+
+@implementation Subclass3
+@end
+
+static int failures = 0;
+
+#define expect(x) do \
+{ \
+	if (!(x)) \
+	{ \
+		fprintf(stderr, "expectation FAILED: %s\n", #x); \
+		++failures; \
+	} \
+} while(0)
+
+int main(int argc, char **argv) {
+	Class firstSuperclass = objc_getClass("DefaultSuperclass");
+	Class subclass1 = objc_getClass("Subclass1");
+
+	/* Transitioning to a new superclass before +initialize has been called */
+	{
+		Class subclass1 = objc_getClass("Subclass1");
+		Class secondSuperclass = objc_getClass("NotInitializedSuperclass1");
+
+		assert(!_notInitializedSuperclass1Initialized);
+		assert(!_subclass1Initialized);
+
+		class_setSuperclass(subclass1, secondSuperclass);
+
+		// assert: dtable has not been installed; new superclass is still not initialized
+		assert(!_notInitializedSuperclass1Initialized);
+
+		[Subclass1 class];
+		// initialization and dtable installation has taken place
+		assert(_notInitializedSuperclass1Initialized);
+
+		Subclass1 *subclass1instance1 = class_createInstance(subclass1, 0);
+
+		// CLASS
+		// can call method on subclass
+		expect([subclass1instance1 existsOnSubclass1]);
+		// can call method on _new_ superclass
+		expect([(id)subclass1instance1 existsOnNotInitializedSuperclass]);
+		// does not respond to selector from original superclass
+		expect(![subclass1 instancesRespondToSelector:@selector(existsOnDefaultSuperclass)]);
+		// *does* respond to selector from new superclass
+		expect([subclass1 instancesRespondToSelector:@selector(existsOnNotInitializedSuperclass)]);
+		// method existing on both old and new superclass kept, IMP updated
+		expect(2 == [subclass1instance1 sameName]);
+		// method existing on subclass, old and new superclass kept, IMP kept
+		expect(5 == [subclass1instance1 overridden]);
+
+	
+		// METACLASS
+		// metaclass does not respond to selector from original meta superclass
+		expect(![subclass1 respondsToSelector:@selector(existsOnDefaultSuperclassMeta)]);
+		// metaclass *does* respond to selector from new meta superclass
+		expect([subclass1 respondsToSelector:@selector(existsOnNotInitializedSuperclassMeta)]);
+		// method existing on both old and new superclass kept, IMP updated
+		expect(12 == [subclass1 sameNameMeta]);
+		// method existing on subclass, old and new superclass kept, IMP kept
+		expect(15 == [subclass1 overriddenMeta]);
+	}
+
+	/* Transitioning to a new superclass when +initialize has already been called */
+	{
+		Class subclass2 = objc_getClass("Subclass2");
+		Class secondSuperclass = objc_getClass("NotInitializedSuperclass2");
+		assert(!_notInitializedSuperclass2Initialized);
+		assert(!_subclass2Initialized);
+
+		[Subclass2 class];
+		[Subclass2Subclass class]; // Make sure the subclass is initialized too.
+		assert(_alreadyInitializedSuperclassInitialized);
+		assert(_subclass2Initialized);
+
+		Subclass2 *subclass2instance1 = class_createInstance(subclass2, 0);
+		assert([subclass2instance1 existsOnSubclass2]);
+
+		class_setSuperclass(subclass2, secondSuperclass);
+		assert(_notInitializedSuperclass2Initialized);
+
+		Subclass2 *subclass2instance2 = class_createInstance(subclass2, 0);
+
+		// CLASS
+		// can call method on subclass
+		expect([subclass2instance1 existsOnSubclass2]);
+		// can call method on _new_ superclass
+		expect([(id)subclass2instance1 existsOnNotInitializedSuperclass]);
+		// does not respond to selector from original superclass
+		expect(![subclass2 instancesRespondToSelector:@selector(existsOnDefaultSuperclass)]);
+		// *does* respond to selector from new superclass
+		expect([subclass2 instancesRespondToSelector:@selector(existsOnNotInitializedSuperclass)]);
+
+		// method existing on both old and new superclass kept, IMP updated
+		expect(3 == [subclass2instance1 sameName]);
+		// method existing on subclass, old and new superclass kept, IMP kept
+		expect(6 == [subclass2instance1 overridden]);
+		// method existing only on subclass preserved
+		expect(100 == [subclass2instance1 intermediateOverride]);
+
+		// METACLASS
+		// metaclass does not respond to selector from original meta superclass
+		expect(![subclass2 respondsToSelector:@selector(existsOnDefaultSuperclassMeta)]);
+		// metaclass *does* respond to selector from new meta superclass
+		expect([subclass2 respondsToSelector:@selector(existsOnNotInitializedSuperclassMeta)]);
+		// method existing on both old and new superclass kept, IMP updated
+		expect(13 == [subclass2 sameNameMeta]);
+		// method existing on subclass, old and new superclass kept, IMP kept
+		expect(16 == [subclass2 overriddenMeta]);
+
+		// SUBCLASS
+		Subclass2 *subclass2subclassInstance = class_createInstance([Subclass2Subclass class], 0);
+		expect(![Subclass2Subclass instancesRespondToSelector:@selector(existsOnDefaultSuperclass)]);
+		expect(![Subclass2Subclass respondsToSelector:@selector(existsOnDefaultSuperclassMeta)]);
+		expect(3 == [subclass2subclassInstance sameName]);
+		expect(6 == [subclass2subclassInstance overridden]);
+		expect(200 == [subclass2subclassInstance intermediateOverride]);
+		expect(13 == [Subclass2Subclass sameNameMeta]);
+		expect(16 == [Subclass2Subclass overriddenMeta]);
+	}
+
+	/* Transitioning ourselves to a new superclass while +initialize is running */
+	{
+		expect(12 == [ChangesDuringInitialize sameNameMeta]);
+		expect(18 == [ChangesDuringInitialize overriddenMeta]);
+	}
+
+	/* Transitioning to a superclass that's in our inheritance hierarchy already */
+	{
+		assert(20 == [MovesUpwardsInHierarchy overriddenMeta]);
+		assert(19 == [MovesUpwardsInHierarchy sameNameMeta]);
+		assert([MovesUpwardsInHierarchy respondsToSelector:@selector(onlyExistsOnRemovedClassMeta)]);
+		assert([MovesUpwardsInHierarchy instancesRespondToSelector:@selector(onlyExistsOnRemovedClass)]);
+
+		class_setSuperclass([MovesUpwardsInHierarchy class], [DefaultSuperclass class]);
+
+		expect(20 == [MovesUpwardsInHierarchy overriddenMeta]); // still overridden
+		expect(14 == [MovesUpwardsInHierarchy sameNameMeta]); // falls back to DefaultSuperclass
+		expect(![MovesUpwardsInHierarchy respondsToSelector:@selector(onlyExistsOnRemovedClassMeta)]);
+		expect(![MovesUpwardsInHierarchy instancesRespondToSelector:@selector(onlyExistsOnRemovedClass)]);
+	}
+
+	/* Transitioning to a superclass that may cause initialize lock contention */
+	{
+		assert(!_otherInitializedClassInitialized);
+		expect(14 == [Subclass3 sameNameMeta]);
+		expect(14 == [Subclass3 overriddenMeta]);
+
+		class_setSuperclass([Subclass3 class], objc_getClass("InitializesOneClassWhileBeingInitialized"));
+
+		expect(_otherInitializedClassInitialized);
+		expect(13 == [Subclass3 sameNameMeta]);
+		expect(13 == [Subclass3 overriddenMeta]);
+	}
+
+	return failures;
+}
diff --git a/arc.m b/arc.m
index e18872b3..0540391a 100644
--- a/arc.m
+++ b/arc.m
@@ -12,9 +12,44 @@
 #import "objc/objc-arc.h"
 #import "objc/blocks_runtime.h"
 
-#ifndef NO_PTHREADS
-#include <pthread.h>
-pthread_key_t ARCThreadKey;
+#if defined(_WIN32)
+// We're using the Fiber-Local Storage APIs on Windows
+// because the TLS APIs won't pass app certification.
+// Additionally, the FLS API surface is 1:1 mapped to
+// the TLS API surface when fibers are not in use.
+#	include "safewindows.h"
+#	define arc_tls_store FlsSetValue
+#	define arc_tls_load FlsGetValue
+#	define TLS_CALLBACK(name) void WINAPI name
+
+typedef DWORD arc_tls_key_t;
+typedef void WINAPI(*arc_cleanup_function_t)(void*);
+static inline arc_tls_key_t arc_tls_key_create(arc_cleanup_function_t cleanupFunction)
+{
+	return FlsAlloc(cleanupFunction);
+}
+
+#else // if defined(_WIN32)
+
+#	ifndef NO_PTHREADS
+#		include <pthread.h>
+#		define arc_tls_store pthread_setspecific
+#		define arc_tls_load pthread_getspecific
+#		define TLS_CALLBACK(name) void name
+
+typedef pthread_key_t arc_tls_key_t;
+typedef void (*arc_cleanup_function_t)(void*);
+static inline arc_tls_key_t arc_tls_key_create(arc_cleanup_function_t cleanupFunction)
+{
+	pthread_key_t key;
+	pthread_key_create(&key, cleanupFunction);
+	return key;
+}
+#	endif
+#endif
+
+#ifdef arc_tls_store
+arc_tls_key_t ARCThreadKey;
 #endif
 
 extern void _NSConcreteMallocBlock;
@@ -60,14 +95,14 @@ - (void)release;
 
 static inline struct arc_tls* getARCThreadData(void)
 {
-#ifdef NO_PTHREADS
+#ifndef arc_tls_store
 	return NULL;
-#else
-	struct arc_tls *tls = pthread_getspecific(ARCThreadKey);
+#else // !defined arc_tls_store
+	struct arc_tls *tls = arc_tls_load(ARCThreadKey);
 	if (NULL == tls)
 	{
 		tls = calloc(sizeof(struct arc_tls), 1);
-		pthread_setspecific(ARCThreadKey, tls);
+		arc_tls_store(ARCThreadKey, tls);
 	}
 	return tls;
 #endif
@@ -133,7 +168,8 @@ static void emptyPool(struct arc_tls *tls, id *stop)
 	//fprintf(stderr, "New insert: %p.  Stop: %p\n", tls->pool->insert, stop);
 }
 
-static void cleanupPools(struct arc_tls* tls)
+#ifdef arc_tls_store
+static TLS_CALLBACK(cleanupPools)(struct arc_tls* tls)
 {
 	if (tls->returnRetained)
 	{
@@ -151,6 +187,7 @@ static void cleanupPools(struct arc_tls* tls)
 	}
 	free(tls);
 }
+#endif
 
 
 static Class AutoreleasePool;
@@ -596,8 +633,8 @@ PRIVATE void init_arc(void)
 {
 	weak_ref_initialize(&weakRefs, 128);
 	INIT_LOCK(weakRefLock);
-#ifndef NO_PTHREADS
-	pthread_key_create(&ARCThreadKey, (void(*)(void*))cleanupPools);
+#ifdef arc_tls_store
+	ARCThreadKey = arc_tls_key_create((arc_cleanup_function_t)cleanupPools);
 #endif
 }
 
diff --git a/associate.m b/associate.m
index fd3317c6..cfae3c80 100644
--- a/associate.m
+++ b/associate.m
@@ -75,14 +75,16 @@ static BOOL isAtomic(uintptr_t policy)
 
 static struct reference* findReference(struct reference_list *list, void *key)
 {
-	if (NULL == list) { return NULL; }
-
-	for (int i=0 ; i<REFERENCE_LIST_SIZE ; i++)
+	while (list)
 	{
-		if (list->list[i].key == key)
+		for (int i=0 ; i<REFERENCE_LIST_SIZE ; i++)
 		{
-			return &list->list[i];
+			if (list->list[i].key == key)
+			{
+				return &list->list[i];
+			}
 		}
+		list = list->next;
 	}
 	return NULL;
 }
@@ -166,12 +168,17 @@ static void setReference(struct reference_list *list,
 		lock = lock_for_pointer(r);
 		lock_spinlock(lock);
 	}
-	r->policy = policy;
-	id old = r->object;
-	r->object = obj;
-	if (OBJC_ASSOCIATION_ASSIGN != r->policy)
+	@try
+	{
+		if (OBJC_ASSOCIATION_ASSIGN != r->policy)
+		{
+			objc_release(r->object);
+		}
+	}
+	@finally
 	{
-		objc_release(old);
+		r->policy = policy;
+		r->object = obj;
 	}
 	if (needLock)
 	{
diff --git a/class.h b/class.h
index a00043e0..339b5c88 100644
--- a/class.h
+++ b/class.h
@@ -410,4 +410,15 @@ static inline Class classForObject(id obj)
 	return obj->isa;
 }
 
+static inline BOOL classIsOrInherits(Class cls, Class base)
+{
+	for (Class c = cls ;
+		Nil != c ;
+		c = c->super_class)
+	{
+		if (c == base) { return YES; }
+	}
+	return NO;
+}
+
 #endif //__OBJC_CLASS_H_INCLUDED
diff --git a/common.S b/common.S
index a8cc09af..4fab30cf 100644
--- a/common.S
+++ b/common.S
@@ -1,4 +1,4 @@
-#if defined(__WIN32__) || defined(__APPLE__)
+#if (defined(_WIN32) && defined(__i386__)) || defined(__APPLE__)
 #define CDECL(symbol) _##symbol
 #else
 #define CDECL(symbol) symbol
diff --git a/dtable.c b/dtable.c
index 112b4f85..5b0aefe6 100644
--- a/dtable.c
+++ b/dtable.c
@@ -392,6 +392,78 @@ PRIVATE void objc_update_dtable_for_class(Class cls)
 	checkARCAccessors(cls);
 }
 
+static void rebaseDtableRecursive(Class cls, Class newSuper)
+{
+	dtable_t parentDtable = dtable_for_class(newSuper);
+	// Collect all of the methods for this class:
+	dtable_t temporaryDtable = SparseArrayNewWithDepth(dtable_depth);
+
+	for (struct objc_method_list *list = cls->methods ; list != NULL ; list = list->next)
+	{
+		for (unsigned i=0 ; i<list->count ; i++)
+		{
+			struct objc_method *m = method_at_index(list, i);
+			uint32_t idx = m->selector->index;
+			// Don't replace existing methods - we're doing the traversal
+			// pre-order so we'll see methods from categories first.
+			if (SparseArrayLookup(temporaryDtable, idx) == NULL)
+			{
+				SparseArrayInsert(temporaryDtable, idx, m);
+			}
+		}
+	}
+
+
+	dtable_t dtable = dtable_for_class(cls);
+	uint32_t idx = 0;
+	struct objc_method *method;
+	// Install all methods in the dtable with the correct ones.
+	while ((method = SparseArrayNext(temporaryDtable, &idx)))
+	{
+		SparseArrayInsert(dtable, idx, method);
+	}
+	idx = 0;
+	// Now look at all of the methods in the dtable.  If they're not ones from
+	// the dtable that we've just created, then they must come from the
+	// superclass, so replace them with whatever the superclass has (which may
+	// be NULL).
+	while ((method = SparseArrayNext(dtable, &idx)))
+	{
+		if (SparseArrayLookup(temporaryDtable, idx) == NULL)
+		{
+			SparseArrayInsert(dtable, idx, SparseArrayLookup(parentDtable, idx));
+		}
+	}
+	SparseArrayDestroy(temporaryDtable);
+
+	// merge can make a class ARC-compatible.
+	checkARCAccessors(cls);
+
+	// Now visit all of our subclasses and propagate the changes downwards.
+	for (struct objc_class *subclass=cls->subclass_list ;
+	     Nil != subclass ; subclass = subclass->sibling_class)
+	{
+		// Don't bother updating dtables for subclasses that haven't been
+		// initialized yet
+		if (!classHasDtable(subclass)) { continue; }
+		rebaseDtableRecursive(subclass, cls);
+	}
+
+}
+
+PRIVATE void objc_update_dtable_for_new_superclass(Class cls, Class newSuper)
+{
+	// Only update real dtables
+	if (!classHasDtable(cls)) { return; }
+
+	LOCK_RUNTIME_FOR_SCOPE();
+	rebaseDtableRecursive(cls, newSuper);
+	// Invalidate all caches after this operation.
+	objc_method_cache_version++;
+
+	return;
+}
+
 PRIVATE void add_method_list_to_class(Class cls,
                                       struct objc_method_list *list)
 {
@@ -410,7 +482,7 @@ PRIVATE void add_method_list_to_class(Class cls,
 	checkARCAccessors(cls);
 }
 
-static dtable_t create_dtable_for_class(Class class, dtable_t root_dtable)
+PRIVATE dtable_t create_dtable_for_class(Class class, dtable_t root_dtable)
 {
 	// Don't create a dtable for a class that already has one
 	if (classHasDtable(class)) { return dtable_for_class(class); }
diff --git a/dtable.h b/dtable.h
index c3748929..d841dbcf 100644
--- a/dtable.h
+++ b/dtable.h
@@ -115,6 +115,11 @@ static inline int classHasDtable(struct objc_class *cls)
  * modifying a class's method list.
  */
 void objc_update_dtable_for_class(Class);
+/**
+ * Updates the dtable for a class and its subclasses.  Must be called after
+ * changing and initializing a class's superclass.
+ */
+void objc_update_dtable_for_new_superclass(Class, Class);
 /**
  * Adds a single method list to a class.  This is used when loading categories,
  * and is faster than completely rebuilding the dtable.
diff --git a/eh_personality.c b/eh_personality.c
index f9a882c6..41d1675f 100644
--- a/eh_personality.c
+++ b/eh_personality.c
@@ -562,7 +562,7 @@ struct thread_data *get_thread_data(void)
 	}
 	return td;
 #else
-	return &td;
+	return &thread_data;
 #endif
 }
 
@@ -572,7 +572,7 @@ struct thread_data *get_thread_data_fast(void)
 	struct thread_data *td = pthread_getspecific(key);
 	return td;
 #else
-	return &td;
+	return &thread_data;
 #endif
 }
 
diff --git a/hash_table.h b/hash_table.h
index aaae7728..efa5cf63 100644
--- a/hash_table.h
+++ b/hash_table.h
@@ -392,6 +392,22 @@ static void PREFIX(_remove)(PREFIX(_table) *table, void *key)
 	MAP_LOCK();
 	PREFIX(_table_cell) cell = PREFIX(_table_get_cell)(table, key);
 	if (NULL == cell) { return; }
+
+	uint32_t hash = MAP_TABLE_HASH_KEY(key);
+	PREFIX(_table_cell) baseCell = PREFIX(_table_lookup)(table, hash);
+	if (baseCell && baseCell <= cell && cell - baseCell <= 32)
+	{
+		uint32_t jump = 1 << (cell - baseCell - 1);
+		if ((baseCell->secondMaps & jump))
+		{
+			// If we are removing a cell stored adjacent to its base due to hash
+			// collision, we have to clear the base cell's neighbor bit.
+			// Otherwise, a later remove can move the new placeholder value to the head
+			// which will cause further chained lookups to fail.
+			baseCell->secondMaps &= ~jump;
+		}
+	}
+
 	// If the cell contains a value, set it to the placeholder and shuffle up
 	// everything
 	if (0 == cell->secondMaps)
diff --git a/lock.h b/lock.h
index d39f07b3..08c0777f 100644
--- a/lock.h
+++ b/lock.h
@@ -6,15 +6,13 @@
 
 #ifndef __LIBOBJC_LOCK_H_INCLUDED__
 #define __LIBOBJC_LOCK_H_INCLUDED__
-#ifdef WIN32
-#define BOOL _WINBOOL
-#	include <windows.h>
-#undef BOOL
-typedef HANDLE mutex_t;
-#	define INIT_LOCK(x) x = CreateMutex(NULL, FALSE, NULL)
-#	define LOCK(x) WaitForSingleObject(*x, INFINITE)
-#	define UNLOCK(x) ReleaseMutex(*x)
-#	define DESTROY_LOCK(x) CloseHandle(*x)
+#ifdef _WIN32
+#	include "safewindows.h"
+typedef CRITICAL_SECTION mutex_t;
+#	define INIT_LOCK(x) InitializeCriticalSection(&(x))
+#	define LOCK(x) EnterCriticalSection(x)
+#	define UNLOCK(x) LeaveCriticalSection(x)
+#	define DESTROY_LOCK(x) DeleteCriticalSection(x)
 #else
 
 #	include <pthread.h>
@@ -49,13 +47,26 @@ __attribute__((unused)) static void objc_release_lock(void *x)
 	mutex_t *lock = *(mutex_t**)x;
 	UNLOCK(lock);
 }
+/**
+ * Concatenate strings during macro expansion.
+ */
+#define LOCK_HOLDERN_NAME_CAT(x, y) x ## y
+/**
+ * Concatenate string with unique variable during macro expansion.
+ */
+#define LOCK_HOLDER_NAME_COUNTER(x, y) LOCK_HOLDERN_NAME_CAT(x, y)
+/**
+ * Create a unique name for a lock holder variable
+ */
+#define LOCK_HOLDER_NAME(x) LOCK_HOLDER_NAME_COUNTER(x, __COUNTER__)
+
 /**
  * Acquires the lock and automatically releases it at the end of the current
  * scope.
  */
 #define LOCK_FOR_SCOPE(lock) \
 	__attribute__((cleanup(objc_release_lock)))\
-	__attribute__((unused)) mutex_t *lock_pointer = lock;\
+	__attribute__((unused)) mutex_t *LOCK_HOLDER_NAME(lock_pointer) = lock;\
 	LOCK(lock)
 
 /**
diff --git a/objc/encoding.h b/objc/encoding.h
index 4c4ff53b..ceccd596 100644
--- a/objc/encoding.h
+++ b/objc/encoding.h
@@ -5,6 +5,10 @@
 #ifndef __LIBOBJC_ENCODING_H_INCLUDED__
 #define __LIBOBJC_ENCODING_H_INCLUDED__
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 const char *objc_skip_type_qualifiers (const char *type);
 
 const char *objc_skip_typespec(const char *type);
@@ -71,4 +75,8 @@ void objc_layout_structure_get_info (struct objc_struct_layout *layout,
 #define _F_ONEWAY      0x10
 #define _F_GCINVISIBLE 0x20
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif // __LIBOBJC_ENCODING_H_INCLUDED__
diff --git a/objc/hooks.h b/objc/hooks.h
index e7bfe25f..f72f1cf9 100644
--- a/objc/hooks.h
+++ b/objc/hooks.h
@@ -2,6 +2,10 @@
 #pragma clang system_header
 #endif
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * This file includes all of the hooks that can be used to alter the behaviour
  * of the runtime.  
@@ -106,4 +110,6 @@ typedef IMP (*objc_tracing_hook)(id, SEL, IMP, int, void*);
  */
 int objc_registerTracingHook(SEL, objc_tracing_hook);
 
-
+#ifdef __cplusplus
+}
+#endif
diff --git a/objc/objc-arc.h b/objc/objc-arc.h
index 32ecb7a9..14f7d000 100644
--- a/objc/objc-arc.h
+++ b/objc/objc-arc.h
@@ -4,6 +4,11 @@
 
 #ifndef __OBJC_ARC_INCLUDED__
 #define __OBJC_ARC_INCLUDED__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * Autoreleases the argument.  Equivalent to [obj autorelease].
  */
@@ -138,5 +143,10 @@ unsigned long objc_arc_autorelease_count_np(void);
  * this thread.
  */
 unsigned long objc_arc_autorelease_count_for_object_np(id);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif // __OBJC_ARC_INCLUDED__
 
diff --git a/objc/runtime.h b/objc/runtime.h
index 299ef80c..e6a93342 100644
--- a/objc/runtime.h
+++ b/objc/runtime.h
@@ -198,7 +198,11 @@ typedef struct
 #ifdef __GNUC
 #	define _OBJC_NULL_PTR __null
 #elif defined(__cplusplus)
-#	define _OBJC_NULL_PTR 0
+#	if __has_feature(cxx_nullptr)
+#		define _OBJC_NULL_PTR nullptr
+#	else
+#		define _OBJC_NULL_PTR 0
+#	endif
 #else
 #	define _OBJC_NULL_PTR ((void*)0)
 #endif
diff --git a/objc_msgSend.x86-32.S b/objc_msgSend.x86-32.S
index 77193bda..7d83a4c7 100644
--- a/objc_msgSend.x86-32.S
+++ b/objc_msgSend.x86-32.S
@@ -54,7 +54,7 @@
 	push  %ecx                           # _cmd
 	push  %eax                           # &self
 	.cfi_def_cfa_offset 12
-	call  slowMsgLookup@PLT
+	call  CDECL(slowMsgLookup)@PLT
 	add   $8, %esp                       # restore the stack
 
 
@@ -65,8 +65,14 @@
 7:
 	popl  %ebx;
 8:
+#if __ELF__
+	# ELF can support GOT-relative addressing;
+	# PE/COFF and Mach-O need a text relocation.
 	addl  $_GLOBAL_OFFSET_TABLE_+(8b-7b), %ebx
 	leal  SmallObjectClasses@GOTOFF(%ebx), %eax
+#else
+	leal  CDECL(SmallObjectClasses), %eax
+#endif
 	mov   (%eax), %eax
 	popl  %ebx
 	jmp   1b 
diff --git a/objcxx_eh.h b/objcxx_eh.h
index 987479c1..024283a0 100644
--- a/objcxx_eh.h
+++ b/objcxx_eh.h
@@ -5,8 +5,18 @@ extern "C" {
  * Allocates a C++ exception.  This function is part of the Itanium C++ ABI and
  * is provided externally.
  */
+/*
+ * Note: Recent versions of libsupc++ already provide a prototype for
+ * __cxa__allocate_exception(). Since the libsupc++ version is defined with
+ * _GLIBCXX_NOTHROW, clang gives a type mismatch error.
+ */
+#ifndef __cplusplus
+#undef CXA_ALLOCATE_EXCEPTION_SPECIFIER
+#define CXA_ALLOCATE_EXCEPTION_SPECIFIER
+#endif
 __attribute__((weak))
-void *__cxa_allocate_exception(size_t thrown_size);
+void *__cxa_allocate_exception(size_t thrown_size) CXA_ALLOCATE_EXCEPTION_SPECIFIER;
+
 /**
  * Initialises an exception object returned by __cxa_allocate_exception() for
  * storing an Objective-C object.  The return value is the location of the
diff --git a/runtime.c b/runtime.c
index 6472c6c7..96ef72ff 100644
--- a/runtime.c
+++ b/runtime.c
@@ -21,6 +21,10 @@
 
 #define CHECK_ARG(arg) if (0 == arg) { return 0; }
 
+static inline void safe_remove_from_subclass_list(Class cls);
+PRIVATE void objc_resolve_class(Class);
+void objc_send_initialize(id object);
+
 /**
  * Calls C++ destructors in the correct order.
  */
@@ -331,7 +335,9 @@ id class_createInstance(Class cls, size_t extraBytes)
 	}
 
 	if (Nil == cls)	{ return nil; }
-	assert(cls->instance_size >= sizeof(Class));
+	// Don't try to allocate an object of size 0, because there's no space for
+	// its isa pointer!
+	if (cls->instance_size < sizeof(Class)) { return nil; }
 	id obj = gc->allocate_class(cls, extraBytes);
 	obj->isa = cls;
 	checkARCAccessorsSlow(cls);
@@ -488,9 +494,58 @@ Class class_setSuperclass(Class cls, Class newSuper)
 {
 	CHECK_ARG(cls);
 	CHECK_ARG(newSuper);
+	Class oldSuper;
 	if (Nil == cls) { return Nil; }
-	Class oldSuper = cls->super_class;
-	cls->super_class = newSuper;
+
+	{
+		LOCK_RUNTIME_FOR_SCOPE();
+
+		oldSuper = cls->super_class;
+
+		if (oldSuper == newSuper) { return newSuper; }
+
+		safe_remove_from_subclass_list(cls);
+		objc_resolve_class(newSuper);
+
+		cls->super_class = newSuper;
+
+		// The super class's subclass list is used in certain method resolution scenarios.
+		cls->sibling_class = cls->super_class->subclass_list;
+		cls->super_class->subclass_list = cls;
+
+		if (UNLIKELY(class_isMetaClass(cls)))
+		{
+			// newSuper is presumably a metaclass. Its isa will therefore be the appropriate root metaclass.
+			cls->isa = newSuper->isa;
+		}
+		else
+		{
+			Class meta = cls->isa, newSuperMeta = newSuper->isa;
+			// Update the metaclass's superclass.
+			safe_remove_from_subclass_list(meta);
+			objc_resolve_class(newSuperMeta);
+
+			meta->super_class = newSuperMeta;
+			meta->isa = newSuperMeta->isa;
+
+			// The super class's subclass list is used in certain method resolution scenarios.
+			meta->sibling_class = newSuperMeta->subclass_list;
+			newSuperMeta->subclass_list = meta;
+		}
+
+		LOCK_FOR_SCOPE(&initialize_lock);
+		if (!objc_test_class_flag(cls, objc_class_flag_initialized))
+		{
+			// Uninitialized classes don't have dtables to update
+			// and don't need their superclasses initialized.
+			return oldSuper;
+		}
+	}
+
+	objc_send_initialize((id)newSuper); // also initializes the metaclass
+	objc_update_dtable_for_new_superclass(cls->isa, newSuper->isa);
+	objc_update_dtable_for_new_superclass(cls, newSuper);
+
 	return oldSuper;
 }
 
@@ -756,8 +811,6 @@ const char *object_getClassName(id obj)
 	return class_getName(object_getClass(obj));
 }
 
-PRIVATE void objc_resolve_class(Class);
-
 void objc_registerClassPair(Class cls)
 {
 	if (cls->ivars != NULL)
diff --git a/safewindows.h b/safewindows.h
new file mode 100644
index 00000000..8a0850d2
--- /dev/null
+++ b/safewindows.h
@@ -0,0 +1,20 @@
+#ifndef __LIBOBJC_SAFEWINDOWS_H_INCLUDED__
+#define __LIBOBJC_SAFEWINDOWS_H_INCLUDED__
+
+#pragma push_macro("BOOL")
+
+#ifdef BOOL
+#undef BOOL
+#endif
+#define BOOL _WINBOOL
+
+#include <Windows.h>
+
+// Windows.h defines interface -> struct
+#ifdef interface
+#undef interface
+#endif
+
+#pragma pop_macro("BOOL")
+
+#endif // __LIBOBJC_SAFEWINDOWS_H_INCLUDED__
diff --git a/spinlock.h b/spinlock.h
index e65e6081..2efec475 100644
--- a/spinlock.h
+++ b/spinlock.h
@@ -1,5 +1,5 @@
-#ifdef __MINGW32__
-#include <windows.h>
+#ifdef _WIN32
+#include "safewindows.h"
 static unsigned sleep(unsigned seconds)
 {
 	Sleep(seconds*1000);
diff --git a/visibility.h b/visibility.h
index 86c379b0..d98d052d 100644
--- a/visibility.h
+++ b/visibility.h
@@ -17,7 +17,7 @@
 #	define ASSERT(x) assert(x)
 #else
 #	define UNREACHABLE(x) __builtin_unreachable()
-#	define ASSERT(x) do { if (x) __builtin_unreachable(); } while(0)
+#	define ASSERT(x) do { if (!(x)) __builtin_unreachable(); } while(0)
 #endif
 
 #define LIKELY(x) __builtin_expect(x, 1)