diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 684fda7440731..35ce3cf1bc81a 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -2841,7 +2841,10 @@ llvm::FunctionCallee CodeGenModule::getBlockObjectDispose() {
   llvm::Type *args[] = { Int8PtrTy, Int32Ty };
   llvm::FunctionType *fty
     = llvm::FunctionType::get(VoidTy, args, false);
-  BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose");
+  llvm::AttributeList AL =
+      getTargetExtAttrs({AttrKind::None, AttrKind::None, AttrKind::SExt});
+  BlockObjectDispose = CreateRuntimeFunction(fty, "_Block_object_dispose", AL);
+  // FIXME: Correct signedness of extension??
   configureBlocksRuntimeObject(
       *this, cast<llvm::Constant>(BlockObjectDispose.getCallee()));
   return BlockObjectDispose;
@@ -2854,7 +2857,9 @@ llvm::FunctionCallee CodeGenModule::getBlockObjectAssign() {
   llvm::Type *args[] = { Int8PtrTy, Int8PtrTy, Int32Ty };
   llvm::FunctionType *fty
     = llvm::FunctionType::get(VoidTy, args, false);
-  BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign");
+  llvm::AttributeList AL = getTargetExtAttrs(
+      {AttrKind::None, AttrKind::None, AttrKind::None, AttrKind::SExt});
+  BlockObjectAssign = CreateRuntimeFunction(fty, "_Block_object_assign", AL);
   configureBlocksRuntimeObject(
       *this, cast<llvm::Constant>(BlockObjectAssign.getCallee()));
   return BlockObjectAssign;
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 25c1c496a4f27..a7e4ce3ba4f7d 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -4755,6 +4755,15 @@ llvm::Constant *CodeGenModule::GetOrCreateLLVMFunction(
     llvm::AttrBuilder B(F->getContext(), ExtraAttrs.getFnAttrs());
     F->addFnAttrs(B);
   }
+  if (ExtraAttrs.hasRetAttrs()) {
+    llvm::AttrBuilder B(F->getContext(), ExtraAttrs.getRetAttrs());
+    F->addRetAttrs(B);
+  }
+  for (unsigned i = 0; i < F->arg_size(); ++i)
+    if (ExtraAttrs.hasParamAttrs(i)) {
+      llvm::AttrBuilder B(F->getContext(), ExtraAttrs.getParamAttrs(i));
+      F->addParamAttrs(i, B);
+    }
 
   if (!DontDefer) {
     // All MSVC dtors other than the base dtor are linkonce_odr and delegate to
@@ -4938,6 +4947,40 @@ CodeGenModule::CreateRuntimeFunction(llvm::FunctionType *FTy, StringRef Name,
   return {FTy, C};
 }
 
+llvm::AttributeList
+CodeGenModule::getTargetExtAttrs(ArrayRef<AttrKind> Extensions) {
+  using AttrIndex = llvm::AttributeList::AttrIndex;
+  assert(Extensions.size() && "Empty array not expected.");
+  const auto &T = getTarget().getTriple();
+  llvm::AttributeList AL;
+
+  bool IsSigned;
+  auto isExtension = [&IsSigned](AttrKind AK) -> bool {
+    assert((AK == AttrKind::None || AK == AttrKind::SExt ||
+            AK == AttrKind::ZExt) &&
+           "Unhandled extension attribute.");
+    if (AK != AttrKind::SExt && AK != AttrKind::ZExt)
+      return false;
+    IsSigned = (AK == AttrKind::SExt);
+    return true;
+  };
+
+  if (isExtension(Extensions[0])) { // Returned value at index 0.
+    AttrKind AK = llvm::TargetLibraryInfo::getExtAttrForI32Return(T, IsSigned);
+    if (AK != AttrKind::None)
+      AL = AL.addAttributeAtIndex(getLLVMContext(), AttrIndex::ReturnIndex, AK);
+  }
+  for (unsigned i = 1; i < Extensions.size(); ++i)
+    if (isExtension(Extensions[i])) {
+      AttrKind AK = llvm::TargetLibraryInfo::getExtAttrForI32Param(T, IsSigned);
+      if (AK != AttrKind::None)
+        AL = AL.addAttributeAtIndex(getLLVMContext(),
+                                    AttrIndex::FirstArgIndex + i - 1, AK);
+    }
+
+  return AL;
+}
+
 /// GetOrCreateLLVMGlobal - If the specified mangled name is not in the module,
 /// create and return an llvm GlobalVariable with the specified type and address
 /// space. If there is something in the module with the specified name, return
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index c58bb88035ca8..4f0f0c4546e1a 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1252,6 +1252,12 @@ class CodeGenModule : public CodeGenTypeCache {
                         llvm::AttributeList ExtraAttrs = llvm::AttributeList(),
                         bool Local = false, bool AssumeConvergent = false);
 
+  /// Return the extension attributes as an AttributeList after any needed
+  /// adjustments for target. The \Param Extensions list begins with the
+  /// return value and then continues with the arguments.
+  using AttrKind = llvm::Attribute::AttrKind;
+  llvm::AttributeList getTargetExtAttrs(ArrayRef<AttrKind> Extensions);
+
   /// Create a new runtime global variable with the specified type and name.
   llvm::Constant *CreateRuntimeVariable(llvm::Type *Ty,
                                         StringRef Name);