diff --git a/llvm/tools/llvm-rc/ResourceScriptParser.cpp b/llvm/tools/llvm-rc/ResourceScriptParser.cpp
index 09c88ff..c66fc4f 100644
--- a/llvm/tools/llvm-rc/ResourceScriptParser.cpp
+++ b/llvm/tools/llvm-rc/ResourceScriptParser.cpp
@@ -114,16 +114,23 @@
 
 // An integer description might consist of a single integer or
 // an arithmetic expression evaluating to the integer. The expressions
-// can contain the following tokens: <int> ( ) + - | & ~. Their meaning
-// is the same as in C++.
+// can contain the following tokens: <int> ( ) + - | & ~ not. Their meaning
+// is the same as in C++ except for 'not' expression.
 // The operators in the original RC implementation have the following
 // precedence:
-//   1) Unary operators (- ~),
+//   1) Unary operators (- ~ not),
 //   2) Binary operators (+ - & |), with no precedence.
 //
+// 'not' expression is mostly useful for style values. It evaluates to 0,
+// but value given to the operator is stored separately from integer value.
+// It's mostly useful for control style expressions and causes bits from
+// default control style to be excluded from generated style. For binary
+// operators the mask from the right operand is applied to the left operand
+// and masks from both operands are combined in operator result.
+//
 // The following grammar is used to parse the expressions Exp1:
 //   Exp1 ::= Exp2 || Exp1 + Exp2 || Exp1 - Exp2 || Exp1 | Exp2 || Exp1 & Exp2
-//   Exp2 ::= -Exp2 || ~Exp2 || Int || (Exp1).
+//   Exp2 ::= -Exp2 || ~Exp2 || not Expr2 || Int || (Exp1).
 // (More conveniently, Exp1 is a non-empty sequence of Exp2 expressions,
 // separated by binary operators.)
 //
@@ -139,12 +146,15 @@
 //    1 => 01 00, -1 => ff ff, --1 => 01 00, ---1 => ff ff;
 //    1 => 01 00, ~1 => fe ff, ~~1 => 01 00, ~~~1 => fe ff.
 
-Expected<RCInt> RCParser::readInt() { return parseIntExpr1(); }
+Expected<RCInt> RCParser::readInt() {
+  ASSIGN_OR_RETURN(Value, parseIntExpr1());
+  return (*Value).getValue();
+}
 
-Expected<RCInt> RCParser::parseIntExpr1() {
+Expected<IntWithNotMask> RCParser::parseIntExpr1() {
   // Exp1 ::= Exp2 || Exp1 + Exp2 || Exp1 - Exp2 || Exp1 | Exp2 || Exp1 & Exp2.
   ASSIGN_OR_RETURN(FirstResult, parseIntExpr2());
-  RCInt Result = *FirstResult;
+  IntWithNotMask Result = *FirstResult;
 
   while (!isEof() && look().isBinaryOp()) {
     auto OpToken = read();
@@ -175,8 +185,8 @@
   return Result;
 }
 
-Expected<RCInt> RCParser::parseIntExpr2() {
-  // Exp2 ::= -Exp2 || ~Exp2 || Int || (Exp1).
+Expected<IntWithNotMask> RCParser::parseIntExpr2() {
+  // Exp2 ::= -Exp2 || ~Exp2 || not Expr2 || Int || (Exp1).
   static const char ErrorMsg[] = "'-', '~', integer or '('";
 
   if (isEof())
@@ -205,6 +215,13 @@
     return *Result;
   }
 
+  case Kind::Identifier: {
+    if (!read().value().equals_lower("not"))
+      return getExpectedError(ErrorMsg, true);
+    ASSIGN_OR_RETURN(Result, parseIntExpr2());
+    return IntWithNotMask(0, (*Result).getValue());
+  }
+
   default:
     return getExpectedError(ErrorMsg);
   }
@@ -539,13 +556,13 @@
   RETURN_IF_ERROR(consumeType(Kind::Comma));
 
   IntOrString Class;
-  Optional<uint32_t> Style;
+  Optional<IntWithNotMask> Style;
   if (ClassUpper == "CONTROL") {
     // CONTROL text, id, class, style, x, y, width, height [, exstyle] [, helpID]
     ASSIGN_OR_RETURN(ClassStr, readString());
     RETURN_IF_ERROR(consumeType(Kind::Comma));
     Class = *ClassStr;
-    ASSIGN_OR_RETURN(StyleVal, readInt());
+    ASSIGN_OR_RETURN(StyleVal, parseIntExpr1());
     RETURN_IF_ERROR(consumeType(Kind::Comma));
     Style = *StyleVal;
   } else {
@@ -557,7 +574,7 @@
 
   if (ClassUpper != "CONTROL") {
     if (consumeOptionalType(Kind::Comma)) {
-      ASSIGN_OR_RETURN(Val, readInt());
+      ASSIGN_OR_RETURN(Val, parseIntExpr1());
       Style = *Val;
     }
   }