diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -622,9 +622,10 @@
   /// an adjacent bitfield if necessary.  The unit in question is usually
   /// a byte, but larger units are used if IsMsStruct.
   unsigned char UnfilledBitsInLastUnit;
-  /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
-  /// of the previous field if it was a bitfield.
-  unsigned char LastBitfieldTypeSize;
+
+  /// LastBitfieldStorageUnitSize - If IsMsStruct, represents the size of the
+  /// storage unit of the previous field if it was a bitfield.
+  unsigned char LastBitfieldStorageUnitSize;
 
   /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
   /// #pragma pack.
@@ -693,7 +694,7 @@
         UnadjustedAlignment(CharUnits::One()), UseExternalLayout(false),
         InferAlignment(false), Packed(false), IsUnion(false),
         IsMac68kAlign(false), IsMsStruct(false), UnfilledBitsInLastUnit(0),
-        LastBitfieldTypeSize(0), MaxFieldAlignment(CharUnits::Zero()),
+        LastBitfieldStorageUnitSize(0), MaxFieldAlignment(CharUnits::Zero()),
         DataSize(0), NonVirtualSize(CharUnits::Zero()),
         NonVirtualAlignment(CharUnits::One()),
         PreferredNVAlignment(CharUnits::One()),
@@ -708,7 +709,7 @@
 
   void LayoutFields(const RecordDecl *D);
   void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
-  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
+  void LayoutWideBitField(uint64_t FieldSize, uint64_t StorageUnitSize,
                           bool FieldPacked, const FieldDecl *D);
   void LayoutBitField(const FieldDecl *D);
 
@@ -1451,7 +1452,7 @@
 }
 
 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
-                                                    uint64_t TypeSize,
+                                                    uint64_t StorageUnitSize,
                                                     bool FieldPacked,
                                                     const FieldDecl *D) {
   assert(Context.getLangOpts().CPlusPlus &&
@@ -1481,7 +1482,7 @@
 
   // We're not going to use any of the unfilled bits in the last byte.
   UnfilledBitsInLastUnit = 0;
-  LastBitfieldTypeSize = 0;
+  LastBitfieldStorageUnitSize = 0;
 
   uint64_t FieldOffset;
   uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
@@ -1520,7 +1521,7 @@
   bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
   uint64_t FieldSize = D->getBitWidthValue(Context);
   TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
-  uint64_t TypeSize = FieldInfo.Width;
+  uint64_t StorageUnitSize = FieldInfo.Width;
   unsigned FieldAlign = FieldInfo.Align;
 
   // UnfilledBitsInLastUnit is the difference between the end of the
@@ -1529,7 +1530,7 @@
   // first bit offset available for non-bitfields).  The current data
   // size in bits is always a multiple of the char size; additionally,
   // for ms_struct records it's also a multiple of the
-  // LastBitfieldTypeSize (if set).
+  // LastBitfieldStorageUnitSize (if set).
 
   // The struct-layout algorithm is dictated by the platform ABI,
   // which in principle could use almost any rules it likes.  In
@@ -1583,26 +1584,26 @@
   // First, some simple bookkeeping to perform for ms_struct structs.
   if (IsMsStruct) {
     // The field alignment for integer types is always the size.
-    FieldAlign = TypeSize;
+    FieldAlign = StorageUnitSize;
 
     // If the previous field was not a bitfield, or was a bitfield
     // with a different storage unit size, or if this field doesn't fit into
     // the current storage unit, we're done with that storage unit.
-    if (LastBitfieldTypeSize != TypeSize ||
+    if (LastBitfieldStorageUnitSize != StorageUnitSize ||
         UnfilledBitsInLastUnit < FieldSize) {
       // Also, ignore zero-length bitfields after non-bitfields.
-      if (!LastBitfieldTypeSize && !FieldSize)
+      if (!LastBitfieldStorageUnitSize && !FieldSize)
         FieldAlign = 1;
 
       UnfilledBitsInLastUnit = 0;
-      LastBitfieldTypeSize = 0;
+      LastBitfieldStorageUnitSize = 0;
     }
   }
 
   // If the field is wider than its declared type, it follows
   // different rules in all cases.
-  if (FieldSize > TypeSize) {
-    LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
+  if (FieldSize > StorageUnitSize) {
+    LayoutWideBitField(FieldSize, StorageUnitSize, FieldPacked, D);
     return;
   }
 
@@ -1686,7 +1687,7 @@
     // Compute the real offset.
     if (FieldSize == 0 ||
         (AllowPadding &&
-         (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
+         (FieldOffset & (FieldAlign - 1)) + FieldSize > StorageUnitSize)) {
       FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
     } else if (ExplicitFieldAlign &&
                (MaxFieldAlignmentInBits == 0 ||
@@ -1700,7 +1701,8 @@
     // Repeat the computation for diagnostic purposes.
     if (FieldSize == 0 ||
         (AllowPadding &&
-         (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
+         (UnpackedFieldOffset & (UnpackedFieldAlign - 1)) + FieldSize >
+             StorageUnitSize))
       UnpackedFieldOffset =
           llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
     else if (ExplicitFieldAlign &&
@@ -1741,11 +1743,11 @@
     // is a zero-width bitfield, in which case just use a size of 1.
     uint64_t RoundedFieldSize;
     if (IsMsStruct) {
-      RoundedFieldSize =
-        (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
+      RoundedFieldSize = (FieldSize ? StorageUnitSize
+                                    : Context.getTargetInfo().getCharWidth());
 
-    // Otherwise, allocate just the number of bytes required to store
-    // the bitfield.
+      // Otherwise, allocate just the number of bytes required to store
+      // the bitfield.
     } else {
       RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
     }
@@ -1757,15 +1759,15 @@
     // We should have cleared UnfilledBitsInLastUnit in every case
     // where we changed storage units.
     if (!UnfilledBitsInLastUnit) {
-      setDataSize(FieldOffset + TypeSize);
-      UnfilledBitsInLastUnit = TypeSize;
+      setDataSize(FieldOffset + StorageUnitSize);
+      UnfilledBitsInLastUnit = StorageUnitSize;
     }
     UnfilledBitsInLastUnit -= FieldSize;
-    LastBitfieldTypeSize = TypeSize;
+    LastBitfieldStorageUnitSize = StorageUnitSize;
 
-  // Otherwise, bump the data size up to include the bitfield,
-  // including padding up to char alignment, and then remember how
-  // bits we didn't use.
+    // Otherwise, bump the data size up to include the bitfield,
+    // including padding up to char alignment, and then remember how
+    // bits we didn't use.
   } else {
     uint64_t NewSizeInBits = FieldOffset + FieldSize;
     uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
@@ -1775,7 +1777,7 @@
     // The only time we can get here for an ms_struct is if this is a
     // zero-width bitfield, which doesn't count as anything for the
     // purposes of unfilled bits.
-    LastBitfieldTypeSize = 0;
+    LastBitfieldStorageUnitSize = 0;
   }
 
   // Update the size.
@@ -1825,7 +1827,7 @@
   uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
   // Reset the unfilled bits.
   UnfilledBitsInLastUnit = 0;
-  LastBitfieldTypeSize = 0;
+  LastBitfieldStorageUnitSize = 0;
 
   bool FieldPacked = Packed || D->hasAttr<PackedAttr>();