diff --git a/include/llvm/IR/Instructions.h b/include/llvm/IR/Instructions.h
index 49b7d472a57..da694f664d9 100644
--- a/include/llvm/IR/Instructions.h
+++ b/include/llvm/IR/Instructions.h
@@ -2160,19 +2160,22 @@ public:
     return cast<Constant>(getOperand(2));
   }
 
-  /// Return the index from the shuffle mask for the specified
-  /// output result.  This is either -1 if the element is undef or a number less
-  /// than 2*numelements.
-  static int getMaskValue(Constant *Mask, unsigned i);
+  /// Return the shuffle mask value for the specified element of the mask.
+  /// Return -1 if the element is undef.
+  static int getMaskValue(Constant *Mask, unsigned Elt);
 
-  int getMaskValue(unsigned i) const {
-    return getMaskValue(getMask(), i);
+  /// Return the shuffle mask value of this instruction for the given element
+  /// index. Return -1 if the element is undef.
+  int getMaskValue(unsigned Elt) const {
+    return getMaskValue(getMask(), Elt);
   }
 
-  /// Return the full mask for this instruction, where each
-  /// element is the element number and undef's are returned as -1.
+  /// Convert the input shuffle mask operand to a vector of integers. Undefined
+  /// elements of the mask are returned as -1.
   static void getShuffleMask(Constant *Mask, SmallVectorImpl<int> &Result);
 
+  /// Return the mask for this instruction as a vector of integers. Undefined
+  /// elements of the mask are returned as -1.
   void getShuffleMask(SmallVectorImpl<int> &Result) const {
     return getShuffleMask(getMask(), Result);
   }
diff --git a/lib/IR/Instructions.cpp b/lib/IR/Instructions.cpp
index 5355f1a617a..89c2caf0dbb 100644
--- a/lib/IR/Instructions.cpp
+++ b/lib/IR/Instructions.cpp
@@ -1908,9 +1908,6 @@ bool ShuffleVectorInst::isValidOperands(const Value *V1, const Value *V2,
   return false;
 }
 
-/// getMaskValue - Return the index from the shuffle mask for the specified
-/// output result.  This is either -1 if the element is undef or a number less
-/// than 2*numelements.
 int ShuffleVectorInst::getMaskValue(Constant *Mask, unsigned i) {
   assert(i < Mask->getType()->getVectorNumElements() && "Index out of range");
   if (ConstantDataSequential *CDS =dyn_cast<ConstantDataSequential>(Mask))
@@ -1921,8 +1918,6 @@ int ShuffleVectorInst::getMaskValue(Constant *Mask, unsigned i) {
   return cast<ConstantInt>(C)->getZExtValue();
 }
 
-/// getShuffleMask - Return the full mask for this instruction, where each
-/// element is the element number and undef's are returned as -1.
 void ShuffleVectorInst::getShuffleMask(Constant *Mask,
                                        SmallVectorImpl<int> &Result) {
   unsigned NumElts = Mask->getType()->getVectorNumElements();