Index: lib/CodeGen/CGObjC.cpp
===================================================================
--- lib/CodeGen/CGObjC.cpp
+++ lib/CodeGen/CGObjC.cpp
@@ -3416,4 +3416,28 @@
   return Builder.CreateICmpNE(CallRes, llvm::Constant::getNullValue(Int32Ty));
 }
 
+void CodeGenModule::emitAtAvailableLinkGuard() {
+  // @available requires CoreFoundation only on Darwin.
+  if (!Target.getTriple().isOSDarwin())
+    return;
+  if (!IsOSVersionAtLeastFn)
+    return;
+  // Emit a reference to a symbol from CoreFoundation to ensure that
+  // CoreFoundation is linked into the final binary.
+  llvm::FunctionType *FTy =
+      llvm::FunctionType::get(Int32Ty, {VoidPtrTy}, false);
+  llvm::Constant *CFFunc =
+      CreateRuntimeFunction(FTy, "CFBundleGetVersionNumber");
+
+  llvm::FunctionType *CheckFTy = llvm::FunctionType::get(VoidTy, {}, false);
+  llvm::Function *CFLinkCheckFunc = cast<llvm::Function>(CreateBuiltinFunction(
+      CheckFTy, "__clang_at_available_requires_core_foundation_framework"));
+  CFLinkCheckFunc->setLinkage(llvm::GlobalValue::LinkOnceAnyLinkage);
+  CodeGenFunction CGF(*this);
+  CGF.Builder.SetInsertPoint(CGF.createBasicBlock("", CFLinkCheckFunc));
+  CGF.EmitNounwindRuntimeCall(CFFunc, llvm::Constant::getNullValue(VoidPtrTy));
+  CGF.Builder.CreateUnreachable();
+  addCompilerUsedGlobal(CFLinkCheckFunc);
+}
+
 CGObjCRuntime::~CGObjCRuntime() {}
Index: lib/CodeGen/CodeGenModule.h
===================================================================
--- lib/CodeGen/CodeGenModule.h
+++ lib/CodeGen/CodeGenModule.h
@@ -1288,6 +1288,10 @@
   /// Emit any vtables which we deferred and still have a use for.
   void EmitDeferredVTables();
 
+  /// Emit a dummy function that reference a CoreFoundation symbol when
+  /// @available is used on Darwin.
+  void emitAtAvailableLinkGuard();
+
   /// Emit the llvm.used and llvm.compiler.used metadata.
   void emitLLVMUsed();
 
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -408,6 +408,7 @@
     CoverageMapping->emit();
   if (CodeGenOpts.SanitizeCfiCrossDso)
     CodeGenFunction(*this).EmitCfiCheckFail();
+  emitAtAvailableLinkGuard();
   emitLLVMUsed();
   if (SanStats)
     SanStats->finish();
Index: test/CodeGenObjC/availability-cf-link-guard.m
===================================================================
--- /dev/null
+++ test/CodeGenObjC/availability-cf-link-guard.m
@@ -0,0 +1,38 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.11 -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.11 -emit-llvm -o - -D USE_BUILTIN %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.11 -emit-llvm -o - -D DEF_CF %s | FileCheck --check-prefix=CHECK_CF %s
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.12 -emit-llvm -o - %s | FileCheck --check-prefix=CHECK_NO_GUARD %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -emit-llvm -o - %s | FileCheck --check-prefix=CHECK_NO_GUARD %s
+
+#ifdef DEF_CF
+struct CFBundle;
+typedef struct CFBundle *CFBundleRef;
+unsigned CFBundleGetVersionNumber(CFBundleRef bundle);
+// CHECK_CF: declare i32 @CFBundleGetVersionNumber(%struct.CFBundle*)
+// CHECK_CF: @__clang_at_available_requires_core_foundation_framework
+// CHECK_CF-NEXT: call {{.*}}@CFBundleGetVersionNumber
+#endif
+
+void use_at_available() {
+#ifdef DEF_CF
+  CFBundleGetVersionNumber(0);
+#endif
+#ifdef USE_BUILTIN
+  if (__builtin_available(macos 10.12, *))
+    ;
+#else
+  if (@available(macos 10.12, *))
+    ;
+#endif
+}
+
+// CHECK: @llvm.compiler.used{{.*}}@__clang_at_available_requires_core_foundation_framework
+
+// CHECK: declare i32 @CFBundleGetVersionNumber(i8*)
+
+// CHECK-LABEL: linkonce void @__clang_at_available_requires_core_foundation_framework
+// CHECK: call i32 @CFBundleGetVersionNumber(i8* null)
+// CHECK-NEXT: unreachable
+
+// CHECK_NO_GUARD-NOT: __clang_at_available_requires_core_foundation_framework
+// CHECK_NO_GUARD-NOT: CFBundleGetVersionNumber