diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp
index 6eb51f0..ed2bf05 100644
--- a/lib/IR/Attributes.cpp
+++ b/lib/IR/Attributes.cpp
@@ -645,6 +645,7 @@
 
 AttributeSet AttributeSet::addAttribute(LLVMContext &C, unsigned Idx,
                                         Attribute::AttrKind Attr) const {
+  if (hasAttribute(Idx, Attr)) return *this;
   return addAttributes(C, Idx, AttributeSet::get(C, Idx, Attr));
 }
 
@@ -699,6 +700,7 @@
 
 AttributeSet AttributeSet::removeAttribute(LLVMContext &C, unsigned Idx,
                                            Attribute::AttrKind Attr) const {
+  if (!hasAttribute(Idx, Attr)) return *this;
   return removeAttributes(C, Idx, AttributeSet::get(C, Idx, Attr));
 }