Index: lib/asan/asan_mac.cc
===================================================================
--- lib/asan/asan_mac.cc
+++ lib/asan/asan_mac.cc
@@ -24,7 +24,15 @@
 #include "sanitizer_common/sanitizer_libc.h"
 #include "sanitizer_common/sanitizer_mac.h"
 
-#include <crt_externs.h>  // for _NSGetArgv
+#if !SANITIZER_IOS
+#include <crt_externs.h>  // for _NSGetArgv and _NSGetEnviron
+#else
+extern char **environ;
+extern "C" {
+  extern char ***_NSGetArgv(void);
+}
+#endif
+
 #include <dlfcn.h>  // for dladdr()
 #include <mach-o/dyld.h>
 #include <mach-o/loader.h>
@@ -62,9 +70,11 @@
 // otherwise the corresponding "NAME=value" string is replaced with
 // |name_value|.
 void LeakyResetEnv(const char *name, const char *name_value) {
+#if !SANITIZER_IOS
   char ***env_ptr = _NSGetEnviron();
   CHECK(env_ptr);
   char **environ = *env_ptr;
+#endif
   CHECK(environ);
   uptr name_len = internal_strlen(name);
   while (*environ != 0) {
Index: lib/asan/asan_mapping.h
===================================================================
--- lib/asan/asan_mapping.h
+++ lib/asan/asan_mapping.h
@@ -98,8 +98,11 @@
 
 static const u64 kDefaultShadowScale = 3;
 static const u64 kDefaultShadowOffset32 = 1ULL << 29;  // 0x20000000
-static const u64 kIosShadowOffset32 = 1ULL << 30;  // 0x40000000
 static const u64 kDefaultShadowOffset64 = 1ULL << 44;
+static const u64 kIosShadowOffset32 = 1ULL << 30;  // 0x40000000
+static const u64 kIosShadowOffset64 = 0x130000000;
+static const u64 kIosSimShadowOffset32 = 1ULL << 30;
+static const u64 kIosSimShadowOffset64 = kDefaultShadowOffset64;
 static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
 static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
 static const u64 kMIPS32_ShadowOffset32 = 0x0aaa0000;
@@ -112,14 +115,26 @@
 #define SHADOW_SCALE kDefaultShadowScale
 #if SANITIZER_ANDROID
 # define SHADOW_OFFSET (0)
+#elif SANITIZER_IOS
+# if SANITIZER_WORDSIZE == 32
+#  if SANITIZER_IOSSIM
+#   define SHADOW_OFFSET kIosSimShadowOffset32
+#  else
+#   define SHADOW_OFFSET kIosShadowOffset32
+#  endif
+# else
+#  if SANITIZER_IOSSIM
+#   define SHADOW_OFFSET kIosSimShadowOffset64
+#  else
+#   define SHADOW_OFFSET kIosShadowOffset64
+#  endif
+# endif
 #else
 # if SANITIZER_WORDSIZE == 32
 #  if defined(__mips__)
 #    define SHADOW_OFFSET kMIPS32_ShadowOffset32
 #  elif SANITIZER_FREEBSD
 #    define SHADOW_OFFSET kFreeBSD_ShadowOffset32
-#  elif SANITIZER_IOS
-#    define SHADOW_OFFSET kIosShadowOffset32
 #  elif SANITIZER_WINDOWS
 #    define SHADOW_OFFSET kWindowsShadowOffset32
 #  else