Index: include/llvm/Support/Endian.h
===================================================================
--- include/llvm/Support/Endian.h
+++ include/llvm/Support/Endian.h
@@ -93,6 +93,16 @@
       (void*)Value.buffer, newValue);
   }
 
+  packed_endian_specific_integral& operator+=(value_type newValue) {
+    *this = *this + newValue;
+    return *this;
+  }
+
+  packed_endian_specific_integral& operator-=(value_type newValue) {
+    *this = *this - newValue;
+    return *this;
+  }
+
 private:
   AlignedCharArray<PickAlignment<value_type, alignment>::value,
                    sizeof(value_type)> Value;