diff --git a/include/llvm/IR/Attributes.h b/include/llvm/IR/Attributes.h
index fbfe5854594..b4056540663 100644
--- a/include/llvm/IR/Attributes.h
+++ b/include/llvm/IR/Attributes.h
@@ -399,6 +399,9 @@ private:
 
   static AttributeList getImpl(LLVMContext &C, ArrayRef<AttributeSet> AttrSets);
 
+  AttributeList setAttributes(LLVMContext &C, unsigned Index,
+                              AttributeSet Attrs) const;
+
 public:
   AttributeList() = default;
 
diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp
index ec2b83f614d..b17673f14c9 100644
--- a/lib/IR/Attributes.cpp
+++ b/lib/IR/Attributes.cpp
@@ -1272,9 +1272,11 @@ AttributeList AttributeList::get(LLVMContext &C,
 AttributeList AttributeList::addAttribute(LLVMContext &C, unsigned Index,
                                           Attribute::AttrKind Kind) const {
   if (hasAttribute(Index, Kind)) return *this;
-  AttrBuilder B;
-  B.addAttribute(Kind);
-  return addAttributes(C, Index, B);
+  AttributeSet Attrs = getAttributes(Index);
+  // TODO: Insert at correct position and avoid sort.
+  SmallVector<Attribute, 8> NewAttrs(Attrs.begin(), Attrs.end());
+  NewAttrs.push_back(Attribute::get(C, Kind));
+  return setAttributes(C, Index, AttributeSet::get(C, NewAttrs));
 }
 
 AttributeList AttributeList::addAttribute(LLVMContext &C, unsigned Index,
@@ -1292,6 +1294,16 @@ AttributeList AttributeList::addAttribute(LLVMContext &C, unsigned Index,
   return addAttributes(C, Index, B);
 }
 
+AttributeList AttributeList::setAttributes(LLVMContext &C, unsigned Index,
+                                           AttributeSet Attrs) const {
+  Index = attrIdxToArrayIdx(Index);
+  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
+  if (Index >= AttrSets.size())
+    AttrSets.resize(Index + 1);
+  AttrSets[Index] = Attrs;
+  return AttributeList::getImpl(C, AttrSets);
+}
+
 AttributeList AttributeList::addAttributes(LLVMContext &C, unsigned Index,
                                            const AttrBuilder &B) const {
   if (!B.hasAttributes())
@@ -1309,16 +1321,9 @@ AttributeList AttributeList::addAttributes(LLVMContext &C, unsigned Index,
          "Attempt to change alignment!");
 #endif
 
-  Index = attrIdxToArrayIdx(Index);
-  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
-  if (Index >= AttrSets.size())
-    AttrSets.resize(Index + 1);
-
-  AttrBuilder Merged(AttrSets[Index]);
+  AttrBuilder Merged(getAttributes(Index));
   Merged.merge(B);
-  AttrSets[Index] = AttributeSet::get(C, Merged);
-
-  return getImpl(C, AttrSets);
+  return setAttributes(C, Index, AttributeSet::get(C, Merged));
 }
 
 AttributeList AttributeList::addParamAttribute(LLVMContext &C,