diff --git a/llvm/include/llvm/Target/TargetLowering.h b/llvm/include/llvm/Target/TargetLowering.h
index ad6fcef765d9..b0534ddaa5e5 100644
--- a/llvm/include/llvm/Target/TargetLowering.h
+++ b/llvm/include/llvm/Target/TargetLowering.h
@@ -634,8 +634,11 @@ public:
 
   /// getOptimalMemOpType - Returns the target specific optimal type for load
   /// and store operations as a result of memset, memcpy, and memmove lowering.
-  /// It returns EVT::Other if SelectionDAG should be responsible for
-  /// determining it.
+  /// If DstAlign is zero that means it's safe to destination alignment can
+  /// satisfy any constraint. Similarly if SrcAlign is zero it means there isn't
+  /// a need to check it against alignment requirement, probably because the
+  /// source does not need to be loaded. It returns EVT::Other if SelectionDAG
+  /// should be responsible for determining it.
   virtual EVT getOptimalMemOpType(uint64_t Size,
                                   unsigned DstAlign, unsigned SrcAlign,
                                   bool SafeToUseFP, SelectionDAG &DAG) const {
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index d043ec626a23..e67666d80481 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -5539,6 +5539,13 @@ PPCTargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
   return false;
 }
 
+/// getOptimalMemOpType - Returns the target specific optimal type for load
+/// and store operations as a result of memset, memcpy, and memmove lowering.
+/// If DstAlign is zero that means it's safe to destination alignment can
+/// satisfy any constraint. Similarly if SrcAlign is zero it means there
+/// isn't a need to check it against alignment requirement, probably because
+/// the source does not need to be loaded. It returns EVT::Other if
+/// SelectionDAG should be responsible for determining it.
 EVT PPCTargetLowering::getOptimalMemOpType(uint64_t Size,
                                            unsigned DstAlign, unsigned SrcAlign,
                                            bool SafeToUseFP,
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index bb2d84ece54c..19fefab2d3a0 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -347,6 +347,13 @@ namespace llvm {
 
     virtual bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const;
     
+    /// getOptimalMemOpType - Returns the target specific optimal type for load
+    /// and store operations as a result of memset, memcpy, and memmove lowering.
+    /// If DstAlign is zero that means it's safe to destination alignment can
+    /// satisfy any constraint. Similarly if SrcAlign is zero it means there
+    /// isn't a need to check it against alignment requirement, probably because
+    /// the source does not need to be loaded. It returns EVT::Other if
+    /// SelectionDAG should be responsible for determining it.
     virtual EVT getOptimalMemOpType(uint64_t Size,
                                     unsigned DstAlign, unsigned SrcAlign,
                                     bool SafeToUseFP, SelectionDAG &DAG) const;
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 5d6e571db126..11d6ec11ba37 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1070,9 +1070,12 @@ unsigned X86TargetLowering::getByValTypeAlignment(const Type *Ty) const {
 }
 
 /// getOptimalMemOpType - Returns the target specific optimal type for load
-/// and store operations as a result of memset, memcpy, and memmove
-/// lowering. It returns MVT::iAny if SelectionDAG should be responsible for
-/// determining it.
+/// and store operations as a result of memset, memcpy, and memmove lowering.
+/// If DstAlign is zero that means it's safe to destination alignment can
+/// satisfy any constraint. Similarly if SrcAlign is zero it means there
+/// isn't a need to check it against alignment requirement, probably because
+/// the source does not need to be loaded. It returns EVT::Other if
+/// SelectionDAG should be responsible for determining it.
 EVT
 X86TargetLowering::getOptimalMemOpType(uint64_t Size,
                                        unsigned DstAlign, unsigned SrcAlign,
diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
index cc7e964f786c..96c3ca2314b5 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.h
+++ b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -420,9 +420,12 @@ namespace llvm {
     virtual unsigned getByValTypeAlignment(const Type *Ty) const;
 
     /// getOptimalMemOpType - Returns the target specific optimal type for load
-    /// and store operations as a result of memset, memcpy, and memmove
-    /// lowering. It returns EVT::iAny if SelectionDAG should be responsible for
-    /// determining it.
+    /// and store operations as a result of memset, memcpy, and memmove lowering.
+    /// If DstAlign is zero that means it's safe to destination alignment can
+    /// satisfy any constraint. Similarly if SrcAlign is zero it means there
+    /// isn't a need to check it against alignment requirement, probably because
+    /// the source does not need to be loaded. It returns EVT::Other if
+    /// SelectionDAG should be responsible for determining it.
     virtual EVT getOptimalMemOpType(uint64_t Size,
                                     unsigned DstAlign, unsigned SrcAlign,
                                     bool SafeToUseFP, SelectionDAG &DAG) const;