diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index 8ceb772..a418a0f 100644
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -120,6 +120,12 @@
     virtual void EmitSymbolAttribute(MCSymbol *Symbol,
                                      SymbolAttr Attribute) = 0;
 
+    /// EmitSymbolDesc - Set the @param DescValue for the @param Symbol.
+    ///
+    /// @param Symbol - The symbol to have its n_desc field set.
+    /// @param DescValue - The value to set into the n_desc field.
+    virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) = 0;
+
     /// EmitCommonSymbol - Emit a common or local common symbol of @param Size
     /// with the @param Pow2Alignment if non-zero.
     ///
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index b8e71ce..b346008 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -45,6 +45,8 @@
 
     virtual void EmitSymbolAttribute(MCSymbol *Symbol, SymbolAttr Attribute);
 
+    virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
+
     virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
                                   unsigned Pow2Alignment, bool IsLocal);
 
@@ -166,6 +168,10 @@
   OS << ' ' << Symbol->getName() << '\n';
 }
 
+void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
+  OS << ".desc" << ' ' << Symbol->getName() << ',' << DescValue << '\n';
+}
+
 void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
                                      unsigned Pow2Alignment, bool IsLocal) {
   if (IsLocal)
diff --git a/test/MC/AsmParser/directive_desc.s b/test/MC/AsmParser/directive_desc.s
new file mode 100644
index 0000000..80acc26
--- /dev/null
+++ b/test/MC/AsmParser/directive_desc.s
@@ -0,0 +1,8 @@
+# RUN: llvm-mc %s | FileCheck %s
+
+# CHECK: TEST0:
+# CHECK: .desc foo,16
+# CHECK: .desc bar,4
+TEST0:  
+	.desc foo,0x10
+	.desc     bar, 1 +3
diff --git a/tools/llvm-mc/AsmParser.cpp b/tools/llvm-mc/AsmParser.cpp
index c105801..d94b7b3 100644
--- a/tools/llvm-mc/AsmParser.cpp
+++ b/tools/llvm-mc/AsmParser.cpp
@@ -526,6 +526,8 @@
       return ParseDirectiveComm(/*IsLocal=*/true);
     if (!strcmp(IDVal, ".zerofill"))
       return ParseDirectiveDarwinZerofill();
+    if (!strcmp(IDVal, ".desc"))
+      return ParseDirectiveDarwinSymbolDesc();
 
     if (!strcmp(IDVal, ".subsections_via_symbols"))
       return ParseDirectiveDarwinSubsectionsViaSymbols();
@@ -909,6 +911,37 @@
   return false;  
 }
 
+/// ParseDirectiveDarwinSymbolDesc
+///  ::= .desc identifier , expression
+bool AsmParser::ParseDirectiveDarwinSymbolDesc() {
+  if (Lexer.isNot(asmtok::Identifier))
+    return TokError("expected identifier in directive");
+  
+  // handle the identifier as the key symbol.
+  SMLoc IDLoc = Lexer.getLoc();
+  MCSymbol *Sym = Ctx.GetOrCreateSymbol(Lexer.getCurStrVal());
+  Lexer.Lex();
+
+  if (Lexer.isNot(asmtok::Comma))
+    return TokError("unexpected token in '.desc' directive");
+  Lexer.Lex();
+
+  SMLoc DescLoc = Lexer.getLoc();
+  int64_t DescValue;
+  if (ParseAbsoluteExpression(DescValue))
+    return true;
+
+  if (Lexer.isNot(asmtok::EndOfStatement))
+    return TokError("unexpected token in '.desc' directive");
+  
+  Lexer.Lex();
+
+  // Set the n_desc field of this Symbol to this DescValue
+  Out.EmitSymbolDesc(Sym, DescValue);
+
+  return false;
+}
+
 /// ParseDirectiveComm
 ///  ::= ( .comm | .lcomm ) identifier , size_expression [ , align_expression ]
 bool AsmParser::ParseDirectiveComm(bool IsLocal) {
diff --git a/tools/llvm-mc/AsmParser.h b/tools/llvm-mc/AsmParser.h
index da54673..b4f5e2d 100644
--- a/tools/llvm-mc/AsmParser.h
+++ b/tools/llvm-mc/AsmParser.h
@@ -109,6 +109,7 @@
   /// ParseDirectiveSymbolAttribute - Parse a directive like ".globl" which
   /// accepts a single symbol (which should be a label or an external).
   bool ParseDirectiveSymbolAttribute(MCStreamer::SymbolAttr Attr);
+  bool ParseDirectiveDarwinSymbolDesc(); // Darwin specific ".desc"
 
   bool ParseDirectiveComm(bool IsLocal); // ".comm" and ".lcomm"
   bool ParseDirectiveDarwinZerofill(); // Darwin specific ".zerofill"