--- a/js/src/asmjs/AsmJSSignalHandlers.cpp
+++ b/js/src/asmjs/AsmJSSignalHandlers.cpp
@@ -196,16 +196,17 @@ class AutoSetHandlingSignal
 # if defined(__FreeBSD__) && defined(__arm__)
 #  define R15_sig(p) ((p)->uc_mcontext.__gregs[_REG_R15])
 # else
 #  define R15_sig(p) ((p)->uc_mcontext.mc_r15)
 # endif
 #elif defined(XP_DARWIN)
 # define EIP_sig(p) ((p)->uc_mcontext->__ss.__eip)
 # define RIP_sig(p) ((p)->uc_mcontext->__ss.__rip)
+# define R15_sig(p) ((p)->uc_mcontext->__ss.__pc)
 #else
 # error "Don't know how to read/write to the thread state via the mcontext_t."
 #endif
 
 #if defined(XP_WIN)
 # include "jswin.h"
 #else
 # include <signal.h>
@@ -315,22 +316,30 @@ enum { REG_EIP = 14 };
 // sigaction-style signal handler.
 #if defined(XP_DARWIN) && defined(ASMJS_MAY_USE_SIGNAL_HANDLERS_FOR_OOB)
 # if defined(JS_CODEGEN_X64)
 struct macos_x64_context {
     x86_thread_state64_t thread;
     x86_float_state64_t float_;
 };
 #  define EMULATOR_CONTEXT macos_x64_context
-# else
+# elif defined(JS_CODEGEN_X86)
 struct macos_x86_context {
     x86_thread_state_t thread;
     x86_float_state_t float_;
 };
 #  define EMULATOR_CONTEXT macos_x86_context
+# elif defined(JS_CODEGEN_ARM)
+struct macos_arm_context {
+    arm_thread_state_t thread;
+    arm_neon_state_t float_;
+};
+#  define EMULATOR_CONTEXT macos_arm_context
+# else
+#  error Unsupported architecture
 # endif
 #else
 # define EMULATOR_CONTEXT CONTEXT
 #endif
 
 #if defined(JS_CPU_X64)
 # define PC_sig(p) RIP_sig(p)
 #elif defined(JS_CPU_X86)
@@ -798,20 +807,26 @@ AsmJSFaultHandler(LPEXCEPTION_POINTERS e
 
 static uint8_t**
 ContextToPC(EMULATOR_CONTEXT* context)
 {
 # if defined(JS_CPU_X64)
     static_assert(sizeof(context->thread.__rip) == sizeof(void*),
                   "stored IP should be compile-time pointer-sized");
     return reinterpret_cast<uint8_t**>(&context->thread.__rip);
-# else
+# elif defined(JS_CPU_X86)
     static_assert(sizeof(context->thread.uts.ts32.__eip) == sizeof(void*),
                   "stored IP should be compile-time pointer-sized");
     return reinterpret_cast<uint8_t**>(&context->thread.uts.ts32.__eip);
+# elif defined(JS_CPU_ARM)
+    static_assert(sizeof(context->thread.__pc) == sizeof(void*),
+                  "stored IP should be compile-time pointer-sized");
+    return reinterpret_cast<uint8_t**>(&context->thread.__pc);
+# else
+#  error Unsupported architecture
 # endif
 }
 
 // This definition was generated by mig (the Mach Interface Generator) for the
 // routine 'exception_raise' (exc.defs).
 #pragma pack(4)
 typedef struct {
     mach_msg_header_t Head;
@@ -847,21 +862,28 @@ HandleMachException(JSRuntime* rt, const
 
     // Read out the JSRuntime thread's register state.
     EMULATOR_CONTEXT context;
 # if defined(JS_CODEGEN_X64)
     unsigned int thread_state_count = x86_THREAD_STATE64_COUNT;
     unsigned int float_state_count = x86_FLOAT_STATE64_COUNT;
     int thread_state = x86_THREAD_STATE64;
     int float_state = x86_FLOAT_STATE64;
-# else
+# elif defined(JS_CODEGEN_X86)
     unsigned int thread_state_count = x86_THREAD_STATE_COUNT;
     unsigned int float_state_count = x86_FLOAT_STATE_COUNT;
     int thread_state = x86_THREAD_STATE;
     int float_state = x86_FLOAT_STATE;
+# elif defined(JS_CODEGEN_ARM)
+    unsigned int thread_state_count = ARM_THREAD_STATE_COUNT;
+    unsigned int float_state_count = ARM_NEON_STATE_COUNT;
+    int thread_state = ARM_THREAD_STATE;
+    int float_state = ARM_NEON_STATE;
+# else
+#  error Unsupported architecture
 # endif
     kern_return_t kret;
     kret = thread_get_state(rtThread, thread_state,
                             (thread_state_t)&context.thread, &thread_state_count);
     if (kret != KERN_SUCCESS)
         return false;
     kret = thread_get_state(rtThread, float_state,
                             (thread_state_t)&context.float_, &float_state_count);

--- a/js/src/irregexp/NativeRegExpMacroAssembler.cpp
+++ b/js/src/irregexp/NativeRegExpMacroAssembler.cpp
@@ -128,16 +128,24 @@ NativeRegExpMacroAssembler::GenerateCode
 
     // Push non-volatile registers which might be modified by jitcode.
     size_t pushedNonVolatileRegisters = 0;
     for (GeneralRegisterForwardIterator iter(savedNonVolatileRegisters); iter.more(); ++iter) {
         masm.Push(*iter);
         pushedNonVolatileRegisters++;
     }
 
+#if defined(XP_IOS) && defined(JS_CODEGEN_ARM)
+    // The stack is 4-byte aligned on iOS, force 8-byte alignment.
+    masm.movePtr(StackPointer, temp0);
+    masm.andPtr(Imm32(~7), StackPointer);
+    masm.push(temp0);
+    masm.push(temp0);
+#endif
+
 #ifndef JS_CODEGEN_X86
     // The InputOutputData* is stored as an argument, save it on the stack
     // above the frame.
     masm.Push(IntArgReg0);
 #endif
 
     size_t frameSize = sizeof(FrameData) + num_registers_ * sizeof(void*);
     frameSize = JS_ROUNDUP(frameSize + masm.framePushed(), ABIStackAlignment) - masm.framePushed();
@@ -364,16 +372,21 @@ NativeRegExpMacroAssembler::GenerateCode
 
 #ifndef JS_CODEGEN_X86
     // Include the InputOutputData* when adjusting the stack size.
     masm.freeStack(frameSize + sizeof(void*));
 #else
     masm.freeStack(frameSize);
 #endif
 
+#if defined(XP_IOS) && defined(JS_CODEGEN_ARM)
+    masm.pop(temp0);
+    masm.movePtr(temp0, StackPointer);
+#endif
+
     // Restore non-volatile registers which were saved on entry.
     for (GeneralRegisterBackwardIterator iter(savedNonVolatileRegisters); iter.more(); ++iter)
         masm.Pop(*iter);
 
     masm.abiret();
 
     // Backtrack code (branch target for conditional backtracks).
     if (backtrack_label_.used()) {

--- a/js/src/jit/ExecutableAllocator.h
+++ b/js/src/jit/ExecutableAllocator.h
@@ -54,16 +54,20 @@ static void sync_instruction_memory(cadd
 extern  "C" void sync_instruction_memory(caddr_t v, u_int len);
 #endif
 #endif
 
 #if defined(JS_CODEGEN_MIPS32) && defined(__linux__) && !defined(JS_SIMULATOR_MIPS32)
 #include <sys/cachectl.h>
 #endif
 
+#if defined(JS_CODEGEN_ARM) && defined(XP_IOS)
+#include <libkern/OSCacheControl.h>
+#endif
+
 namespace JS {
     struct CodeSizes;
 } // namespace JS
 
 namespace js {
 namespace jit {
   enum CodeKind { ION_CODE = 0, BASELINE_CODE, REGEXP_CODE, OTHER_CODE };
 
@@ -404,16 +408,21 @@ class ExecutableAllocator
         _flush_cache(reinterpret_cast<char*>(code), size, BCACHE);
 #endif
     }
 #elif defined(JS_CODEGEN_ARM) && (defined(__FreeBSD__) || defined(__NetBSD__))
     static void cacheFlush(void* code, size_t size)
     {
         __clear_cache(code, reinterpret_cast<char*>(code) + size);
     }
+#elif defined(JS_CODEGEN_ARM) && defined(XP_IOS)
+    static void cacheFlush(void* code, size_t size)
+    {
+        sys_icache_invalidate(code, size);
+    }
 #elif defined(JS_CODEGEN_ARM) && (defined(__linux__) || defined(ANDROID)) && defined(__GNUC__)
     static void cacheFlush(void* code, size_t size)
     {
         asm volatile (
             "push    {r7}\n"
             "mov     r0, %0\n"
             "mov     r1, %1\n"
             "mov     r7, #0xf0000\n"

--- a/js/src/jit/arm/Architecture-arm.cpp
+++ b/js/src/jit/arm/Architecture-arm.cpp
@@ -1,17 +1,17 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jit/arm/Architecture-arm.h"
 
-#ifndef JS_SIMULATOR_ARM
+#if !defined(JS_ARM_SIMULATOR) && !defined(__APPLE__)
 #include <elf.h>
 #endif
 
 #include <fcntl.h>
 #include <unistd.h>
 
 #include "jit/arm/Assembler-arm.h"
 #include "jit/RegisterSets.h"
@@ -240,16 +240,25 @@ InitARMFlags()
     flags |= HWCAP_VFP;
 #endif
 
 #if defined(__ARM_ARCH_7__) || defined (__ARM_ARCH_7A__)
     // Compiled to use ARMv7 instructions so assume the ARMv7 arch.
     flags |= HWCAP_ARMv7;
 #endif
 
+#if defined(__APPLE__)
+    #if defined(__ARM_NEON__)
+        flags |= HWCAP_NEON;
+    #endif
+    #if defined(__ARMVFPV3__)
+        flags |= HWCAP_VFPv3 | HWCAP_VFPD32
+    #endif
+#endif
+
 #endif // JS_SIMULATOR_ARM
 
     armHwCapFlags = CanonicalizeARMHwCapFlags(flags);
 
     JitSpew(JitSpew_Codegen, "ARM HWCAP: 0x%x\n", armHwCapFlags);
     return;
 }
 

--- a/js/src/jit/arm/Architecture-arm.h
+++ b/js/src/jit/arm/Architecture-arm.h
@@ -10,18 +10,19 @@
 #include "mozilla/MathAlgorithms.h"
 
 #include <limits.h>
 #include <stdint.h>
 
 #include "js/Utility.h"
 
 // GCC versions 4.6 and above define __ARM_PCS_VFP to denote a hard-float
-// ABI target.
-#if defined(__ARM_PCS_VFP)
+// ABI target. The iOS toolchain doesn't define anything specific here,
+// but iOS always supports VFP.
+#if defined(__ARM_PCS_VFP) || defined(XP_IOS)
 #define JS_CODEGEN_ARM_HARDFP
 #endif
 
 namespace js {
 namespace jit {
 
 // In bytes: slots needed for potential memory->memory move spills.
 //   +8 for cycles
@@ -104,25 +105,32 @@ class Registers
 
     static const SetType AllMask = (1 << Total) - 1;
     static const SetType ArgRegMask = (1 << r0) | (1 << r1) | (1 << r2) | (1 << r3);
 
     static const SetType VolatileMask =
         (1 << r0) |
         (1 << r1) |
         (1 << Registers::r2) |
-        (1 << Registers::r3);
+        (1 << Registers::r3)
+#if defined(XP_IOS)
+        // per https://developer.apple.com/library/ios/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARMv6FunctionCallingConventions.html#//apple_ref/doc/uid/TP40009021-SW4
+        | (1 << Registers::r9)
+#endif
+              ;
 
     static const SetType NonVolatileMask =
         (1 << Registers::r4) |
         (1 << Registers::r5) |
         (1 << Registers::r6) |
         (1 << Registers::r7) |
         (1 << Registers::r8) |
+#if !defined(XP_IOS)
         (1 << Registers::r9) |
+#endif
         (1 << Registers::r10) |
         (1 << Registers::r11) |
         (1 << Registers::r12) |
         (1 << Registers::r14);
 
     static const SetType WrapperMask =
         VolatileMask |         // = arguments
         (1 << Registers::r4) | // = outReg

new file mode 100644
--- /dev/null
+++ b/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_idivmod.S
@@ -0,0 +1,27 @@
+//===-- aeabi_idivmod.S - EABI idivmod implementation ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../assembly.h"
+
+// struct { int quot, int rem} __aeabi_idivmod(int numerator, int denominator) {
+//   int rem, quot;
+//   quot = __divmodsi4(numerator, denominator, &rem);
+//   return {quot, rem};
+// }
+
+        .syntax unified
+        .align 2
+DEFINE_COMPILERRT_FUNCTION(__aeabi_idivmod)
+        push    { lr }
+        sub     sp, sp, #4
+        mov     r2, sp
+        bl      SYMBOL_NAME(__divmodsi4)
+        ldr     r1, [sp]
+        add     sp, sp, #4
+        pop     { pc }

new file mode 100644
--- /dev/null
+++ b/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_uidivmod.S
@@ -0,0 +1,28 @@
+//===-- aeabi_uidivmod.S - EABI uidivmod implementation -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../assembly.h"
+
+// struct { unsigned quot, unsigned rem}
+//        __aeabi_uidivmod(unsigned numerator, unsigned denominator) {
+//   unsigned rem, quot;
+//   quot = __udivmodsi4(numerator, denominator, &rem);
+//   return {quot, rem};
+// }
+
+        .syntax unified
+        .align 2
+DEFINE_COMPILERRT_FUNCTION(__aeabi_uidivmod)
+        push    { lr }
+        sub     sp, sp, #4
+        mov     r2, sp
+        bl      SYMBOL_NAME(__udivmodsi4)
+        ldr     r1, [sp]
+        add     sp, sp, #4
+        pop     { pc }

new file mode 100644
--- /dev/null
+++ b/js/src/jit/arm/llvm-compiler-rt/assembly.h
@@ -0,0 +1,70 @@
+/* ===-- assembly.h - compiler-rt assembler support macros -----------------===
+ *
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file defines macros for use in compiler-rt assembler source.
+ * This file is not part of the interface of this library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#ifndef COMPILERRT_ASSEMBLY_H
+#define COMPILERRT_ASSEMBLY_H
+
+#if defined(__POWERPC__) || defined(__powerpc__) || defined(__ppc__)
+#define SEPARATOR @
+#else
+#define SEPARATOR ;
+#endif
+
+#if defined(__APPLE__)
+#define HIDDEN_DIRECTIVE .private_extern
+#define LOCAL_LABEL(name) L_##name
+#else
+#define HIDDEN_DIRECTIVE .hidden
+#define LOCAL_LABEL(name) .L_##name
+#endif
+
+#define GLUE2(a, b) a ## b
+#define GLUE(a, b) GLUE2(a, b)
+#define SYMBOL_NAME(name) GLUE(__USER_LABEL_PREFIX__, name)
+
+#ifdef VISIBILITY_HIDDEN
+#define DECLARE_SYMBOL_VISIBILITY(name)                    \
+  HIDDEN_DIRECTIVE SYMBOL_NAME(name) SEPARATOR
+#else
+#define DECLARE_SYMBOL_VISIBILITY(name)
+#endif
+
+#define DEFINE_COMPILERRT_FUNCTION(name)                   \
+  .globl SYMBOL_NAME(name) SEPARATOR                       \
+  DECLARE_SYMBOL_VISIBILITY(name)                          \
+  SYMBOL_NAME(name):
+
+#define DEFINE_COMPILERRT_PRIVATE_FUNCTION(name)           \
+  .globl SYMBOL_NAME(name) SEPARATOR                       \
+  HIDDEN_DIRECTIVE SYMBOL_NAME(name) SEPARATOR             \
+  SYMBOL_NAME(name):
+
+#define DEFINE_COMPILERRT_PRIVATE_FUNCTION_UNMANGLED(name) \
+  .globl name SEPARATOR                                    \
+  HIDDEN_DIRECTIVE name SEPARATOR                          \
+  name:
+
+#define DEFINE_COMPILERRT_FUNCTION_ALIAS(name, target)     \
+  .globl SYMBOL_NAME(name) SEPARATOR                       \
+  .set SYMBOL_NAME(name), SYMBOL_NAME(target) SEPARATOR
+
+#if defined (__ARM_EABI__)
+# define DEFINE_AEABI_FUNCTION_ALIAS(aeabi_name, name)      \
+  DEFINE_COMPILERRT_FUNCTION_ALIAS(aeabi_name, name)
+#else
+# define DEFINE_AEABI_FUNCTION_ALIAS(aeabi_name, name)
+#endif
+
+#endif /* COMPILERRT_ASSEMBLY_H */

--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -433,16 +433,21 @@ elif CONFIG['JS_CODEGEN_ARM']:
         'jit/arm/MoveEmitter-arm.cpp',
         'jit/arm/SharedIC-arm.cpp',
         'jit/arm/Trampoline-arm.cpp',
     ]
     if CONFIG['JS_SIMULATOR_ARM']:
         UNIFIED_SOURCES += [
             'jit/arm/Simulator-arm.cpp'
         ]
+    elif CONFIG['OS_ARCH'] == 'Darwin':
+        SOURCES += [
+            'jit/arm/llvm-compiler-rt/arm/aeabi_idivmod.S',
+            'jit/arm/llvm-compiler-rt/arm/aeabi_uidivmod.S',
+        ]
 elif CONFIG['JS_CODEGEN_ARM64']:
     UNIFIED_SOURCES += [
         'jit/arm64/Architecture-arm64.cpp',
         'jit/arm64/Assembler-arm64.cpp',
         'jit/arm64/Bailouts-arm64.cpp',
         'jit/arm64/BaselineIC-arm64.cpp',
         'jit/arm64/CodeGenerator-arm64.cpp',
         'jit/arm64/Lowering-arm64.cpp',