diff --git a/clang/lib/CodeGen/CodeGenTBAA.h b/clang/lib/CodeGen/CodeGenTBAA.h
--- a/clang/lib/CodeGen/CodeGenTBAA.h
+++ b/clang/lib/CodeGen/CodeGenTBAA.h
@@ -146,6 +146,12 @@
   /// considered to be equivalent to it.
   llvm::MDNode *getChar();
 
+  /// AddCollectedField - Add one collected field to Fields vector
+  void
+  AddCollectedField(SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &Fields,
+                    uint64_t Offset, uint64_t Size, QualType QTy, bool MayAlias,
+                    bool FuseOverlapping);
+
   /// CollectFields - Collect information about the fields of a type for
   /// !tbaa.struct metadata formation. Return false for an unsupported type.
   bool CollectFields(uint64_t BaseOffset,
diff --git a/clang/lib/CodeGen/CodeGenTBAA.cpp b/clang/lib/CodeGen/CodeGenTBAA.cpp
--- a/clang/lib/CodeGen/CodeGenTBAA.cpp
+++ b/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -272,13 +272,28 @@
                         Size);
 }
 
+void CodeGenTBAA::AddCollectedField(
+    SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &Fields, uint64_t Offset,
+    uint64_t Size, QualType QTy, bool MayAlias, bool FuseOverlapping) {
+
+  // Fuse fields that overlap in their byte position (e.g. caused by bitfields)
+  if (FuseOverlapping && !Fields.empty() && Offset < Fields.back().Offset + Fields.back().Size) {
+    Fields.back().Size = Fields.back().Offset - Offset + Size;
+    return;
+  }
+
+  llvm::MDNode *TBAAType = MayAlias ? getChar() : getTypeInfo(QTy);
+  llvm::MDNode *TBAATag = getAccessTagInfo(TBAAAccessInfo(TBAAType, Size));
+  Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size, TBAATag));
+}
+
 bool
 CodeGenTBAA::CollectFields(uint64_t BaseOffset,
                            QualType QTy,
                            SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &
                              Fields,
                            bool MayAlias) {
-  /* Things not handled yet include: C++ base classes, bitfields, */
+  /* Things not handled yet include: C++ base classes */
 
   if (const RecordType *TTy = QTy->getAs<RecordType>()) {
     const RecordDecl *RD = TTy->getDecl()->getDefinition();
@@ -300,19 +315,25 @@
       uint64_t Offset = BaseOffset +
                         Layout.getFieldOffset(idx) / Context.getCharWidth();
       QualType FieldQTy = i->getType();
-      if (!CollectFields(Offset, FieldQTy, Fields,
-                         MayAlias || TypeHasMayAlias(FieldQTy)))
-        return false;
+      bool FieldMayAlias = MayAlias || TypeHasMayAlias(FieldQTy);
+      if ((*i)->isBitField()) {
+        uint64_t EndOffset =
+            BaseOffset +
+            (Layout.getFieldOffset(idx) + (*i)->getBitWidthValue(Context) - 1) /
+                Context.getCharWidth();
+
+        AddCollectedField(Fields, Offset, EndOffset - Offset + 1, QTy, FieldMayAlias, true);
+      } else {
+        if (!CollectFields(Offset, FieldQTy, Fields, FieldMayAlias))
+          return false;
+      }
     }
     return true;
   }
 
   /* Otherwise, treat whatever it is as a field. */
-  uint64_t Offset = BaseOffset;
   uint64_t Size = Context.getTypeSizeInChars(QTy).getQuantity();
-  llvm::MDNode *TBAAType = MayAlias ? getChar() : getTypeInfo(QTy);
-  llvm::MDNode *TBAATag = getAccessTagInfo(TBAAAccessInfo(TBAAType, Size));
-  Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size, TBAATag));
+  AddCollectedField(Fields, BaseOffset, Size, QTy, MayAlias, false);
   return true;
 }