Index: clang/lib/Basic/Targets/OSTargets.h
===================================================================
--- clang/lib/Basic/Targets/OSTargets.h
+++ clang/lib/Basic/Targets/OSTargets.h
@@ -95,16 +95,22 @@
     if (Triple.isMacOSX())
       this->TLSSupported = !Triple.isMacOSXVersionLT(10, 7);
     else if (Triple.isiOS()) {
-      // 64-bit iOS supported it from 8 onwards, 32-bit from 9 onwards.
-      if (Triple.getArch() == llvm::Triple::x86_64 ||
-          Triple.getArch() == llvm::Triple::aarch64)
+      // 64-bit iOS supported it from 8 onwards, 32-bit device from 9 onwards,
+      // 32-bit simulator from 10 onwards.
+      if (Triple.isArch64Bit())
         this->TLSSupported = !Triple.isOSVersionLT(8);
-      else if (Triple.getArch() == llvm::Triple::x86 ||
-               Triple.getArch() == llvm::Triple::arm ||
-               Triple.getArch() == llvm::Triple::thumb)
-        this->TLSSupported = !Triple.isOSVersionLT(9);
-    } else if (Triple.isWatchOS())
-      this->TLSSupported = !Triple.isOSVersionLT(2);
+      else if (Triple.isArch32Bit()) {
+        if (!Triple.isSimulatorEnvironment())
+          this->TLSSupported = !Triple.isOSVersionLT(9);
+        else
+          this->TLSSupported = !Triple.isOSVersionLT(10);
+      }
+    } else if (Triple.isWatchOS()) {
+      if (!Triple.isSimulatorEnvironment())
+        this->TLSSupported = !Triple.isOSVersionLT(2);
+      else
+        this->TLSSupported = !Triple.isOSVersionLT(3);
+    }
 
     this->MCountName = "\01mcount";
   }
Index: clang/test/Sema/darwin-tls.c
===================================================================
--- clang/test/Sema/darwin-tls.c
+++ clang/test/Sema/darwin-tls.c
@@ -1,12 +1,18 @@
 // RUN: not %clang_cc1 -fsyntax-only -triple x86_64-apple-macosx10.6 %s 2>&1 | FileCheck %s --check-prefix NO-TLS
 // RUN: %clang_cc1 -fsyntax-only -triple x86_64-apple-macosx10.7 %s 2>&1 | FileCheck %s --check-prefix TLS
+
 // RUN: not %clang_cc1 -fsyntax-only -triple arm64-apple-ios7.1 %s 2>&1 | FileCheck %s --check-prefix NO-TLS
 // RUN: %clang_cc1 -fsyntax-only -triple arm64-apple-ios8.0 %s 2>&1 | FileCheck %s --check-prefix TLS
 // RUN: not %clang_cc1 -fsyntax-only -triple thumbv7s-apple-ios8.3 %s 2>&1 | FileCheck %s --check-prefix NO-TLS
 // RUN: %clang_cc1 -fsyntax-only -triple thumbv7s-apple-ios9.0 %s 2>&1 | FileCheck %s --check-prefix TLS
 // RUN: %clang_cc1 -fsyntax-only -triple armv7-apple-ios9.0 %s 2>&1 | FileCheck %s --check-prefix TLS
+// RUN: not %clang_cc1 -fsyntax-only -triple i386-apple-ios9.0-simulator %s 2>&1 | FileCheck %s --check-prefix NO-TLS
+// RUN: %clang_cc1 -fsyntax-only -triple i386-apple-ios10.0-simulator %s 2>&1 | FileCheck %s --check-prefix TLS
+
 // RUN: not %clang_cc1 -fsyntax-only -triple thumbv7k-apple-watchos1.0 %s 2>&1 | FileCheck %s --check-prefix NO-TLS
 // RUN: %clang_cc1 -fsyntax-only -triple thumbv7k-apple-watchos2.0 %s 2>&1 | FileCheck %s --check-prefix TLS
+// RUN: not %clang_cc1 -fsyntax-only -triple i386-apple-watchos2.0-simulator %s 2>&1 | FileCheck %s --check-prefix NO-TLS
+// RUN: %clang_cc1 -fsyntax-only -triple i386-apple-watchos3.0-simulator %s 2>&1 | FileCheck %s --check-prefix TLS
 
 
 __thread int a;