diff --git a/tools/llvm-mc/AsmLexer.cpp b/tools/llvm-mc/AsmLexer.cpp
index 740215b..36faeb3 100644
--- a/tools/llvm-mc/AsmLexer.cpp
+++ b/tools/llvm-mc/AsmLexer.cpp
@@ -235,6 +235,7 @@
   case ':': return asmtok::Colon;
   case '+': return asmtok::Plus;
   case '-': return asmtok::Minus;
+  case '~': return asmtok::Tilde;
   case '(': return asmtok::LParen;
   case ')': return asmtok::RParen;
   case '*': return asmtok::Star;
diff --git a/tools/llvm-mc/AsmLexer.h b/tools/llvm-mc/AsmLexer.h
index bad2cb9..a6c9323 100644
--- a/tools/llvm-mc/AsmLexer.h
+++ b/tools/llvm-mc/AsmLexer.h
@@ -39,8 +39,7 @@
     // No-value.
     EndOfStatement,
     Colon,
-    Plus,
-    Minus,
+    Plus, Minus, Tilde,
     Slash,    // '/'
     LParen, RParen,
     Star, Comma, Dollar
diff --git a/tools/llvm-mc/AsmParser.cpp b/tools/llvm-mc/AsmParser.cpp
index c958354..397c5fe 100644
--- a/tools/llvm-mc/AsmParser.cpp
+++ b/tools/llvm-mc/AsmParser.cpp
@@ -213,10 +213,25 @@
   return false;
 }
 
+/// ParseParenExpr - Parse a paren expression and return it.
+/// NOTE: This assumes the leading '(' has already been consumed.
+///
+/// parenexpr ::= expr)
+///
+bool AsmParser::ParseParenExpr(int64_t &Res) {
+  if (ParseExpression(Res)) return true;
+  if (Lexer.isNot(asmtok::RParen))
+    return TokError("expected ')' in parentheses expression");
+  Lexer.Lex();
+  return false;
+}
 
-/// ParseExpression - Parse an expression and return it.
-/// FIXME: This should handle real expressions, we do something trivial for now.
-bool AsmParser::ParseExpression(int64_t &Res) {
+/// ParsePrimaryExpr - Parse a primary expression and return it.
+///  primaryexpr ::= (parenexpr
+///  primaryexpr ::= symbol
+///  primaryexpr ::= number
+///  primaryexpr ::= ~,+,- primaryexpr
+bool AsmParser::ParsePrimaryExpr(int64_t &Res) {
   switch (Lexer.getKind()) {
   default:
     return TokError("unknown token in expression");
@@ -230,8 +245,27 @@
     Res = Lexer.getCurIntVal();
     Lexer.Lex(); // Eat identifier.
     return false;
+  case asmtok::LParen:
+    Lexer.Lex(); // Eat the '('.
+    return ParseParenExpr(Res);
+  case asmtok::Tilde:
+  case asmtok::Plus:
+  case asmtok::Minus:
+    Lexer.Lex(); // Eat the operator.
+    return ParsePrimaryExpr(Res);
   }
 }
+
+/// ParseExpression - Parse an expression and return it.
+/// 
+///  expr ::= expr +,- expr          -> lowest.
+///  expr ::= expr |,^,&,! expr      -> middle.
+///  expr ::= expr *,/,%,<<,>> expr  -> highest.
+///  expr ::= primaryexpr
+///
+bool AsmParser::ParseExpression(int64_t &Res) {
+  return ParsePrimaryExpr(Res);
+}
   
   
   
diff --git a/tools/llvm-mc/AsmParser.h b/tools/llvm-mc/AsmParser.h
index 670d987..82eb433 100644
--- a/tools/llvm-mc/AsmParser.h
+++ b/tools/llvm-mc/AsmParser.h
@@ -39,6 +39,8 @@
   bool ParseX86Operand(X86Operand &Op);
   bool ParseX86MemOperand(X86Operand &Op);
   bool ParseExpression(int64_t &Res);
+  bool ParsePrimaryExpr(int64_t &Res);
+  bool ParseParenExpr(int64_t &Res);
 };
 
 } // end namespace llvm
diff --git a/tools/llvm-mc/llvm-mc.cpp b/tools/llvm-mc/llvm-mc.cpp
index 7d0c571..52205c4 100644
--- a/tools/llvm-mc/llvm-mc.cpp
+++ b/tools/llvm-mc/llvm-mc.cpp
@@ -99,6 +99,7 @@
     case asmtok::Colon:  outs() << "Colon\n"; break;
     case asmtok::Plus:   outs() << "Plus\n"; break;
     case asmtok::Minus:  outs() << "Minus\n"; break;
+    case asmtok::Tilde:  outs() << "Tilde\n"; break;
     case asmtok::Slash:  outs() << "Slash\n"; break;
     case asmtok::LParen: outs() << "LParen\n"; break;
     case asmtok::RParen: outs() << "RParen\n"; break;