Index: llvm/trunk/include/llvm/MC/MCStreamer.h
===================================================================
--- llvm/trunk/include/llvm/MC/MCStreamer.h
+++ llvm/trunk/include/llvm/MC/MCStreamer.h
@@ -682,6 +682,8 @@
   virtual void EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except);
   virtual void EmitWinEHHandlerData();
 
+  virtual void EmitSyntaxDirective();
+
   /// \brief Emit the given \p Instruction into the current section.
   virtual void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI);
 
Index: llvm/trunk/lib/MC/MCAsmStreamer.cpp
===================================================================
--- llvm/trunk/lib/MC/MCAsmStreamer.cpp
+++ llvm/trunk/lib/MC/MCAsmStreamer.cpp
@@ -78,6 +78,9 @@
     }
     EmitCommentsAndEOL();
   }
+
+  virtual void EmitSyntaxDirective();
+
   void EmitCommentsAndEOL();
 
   /// isVerboseAsm - Return true if this streamer supports verbose assembly at
@@ -480,6 +483,14 @@
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitSyntaxDirective() {
+  if (MAI->getAssemblerDialect() == 1)
+    OS << "\t.intel_syntax noprefix\n";
+  // FIXME: Currently emit unprefix'ed registers.
+  // The intel_syntax directive has one optional argument 
+  // with may have a value of prefix or noprefix.
+}
+
 void MCAsmStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
   OS << "\t.def\t ";
   Symbol->print(OS, MAI);
Index: llvm/trunk/lib/MC/MCStreamer.cpp
===================================================================
--- llvm/trunk/lib/MC/MCStreamer.cpp
+++ llvm/trunk/lib/MC/MCStreamer.cpp
@@ -467,6 +467,8 @@
     report_fatal_error("Chained unwind areas can't have handlers!");
 }
 
+void MCStreamer::EmitSyntaxDirective() {}
+
 void MCStreamer::EmitWinCFIPushReg(unsigned Register) {
   EnsureValidWinFrameInfo();
 
Index: llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp
+++ llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp
@@ -535,6 +535,7 @@
           S, MCConstantExpr::create(int64_t(1), MMI->getContext()));
     }
   }
+  OutStreamer->EmitSyntaxDirective();
 }
 
 static void
Index: llvm/trunk/test/MC/X86/intel-syntax-print.ll
===================================================================
--- llvm/trunk/test/MC/X86/intel-syntax-print.ll
+++ llvm/trunk/test/MC/X86/intel-syntax-print.ll
@@ -0,0 +1,9 @@
+; RUN: llc -x86-asm-syntax=intel < %s | FileCheck %s -check-prefix=INTEL
+; RUN: llc -x86-asm-syntax=att < %s | FileCheck %s -check-prefix=ATT
+
+; INTEL: .intel_syntax noprefix
+; ATT-NOT: .intel_syntax noprefix
+define i32 @test() {
+entry:
+  ret i32 0
+}