diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -34,6 +34,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/X86TargetParser.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <memory>
@@ -939,6 +940,7 @@
                           SMLoc End, unsigned Size, StringRef Identifier,
                           const InlineAsmIdentifierInfo &Info);
 
+  bool parseDirectiveArch();
   bool parseDirectiveEven(SMLoc L);
   bool ParseDirectiveCode(StringRef IDVal, SMLoc L);
 
@@ -3973,6 +3975,8 @@
 bool X86AsmParser::ParseDirective(AsmToken DirectiveID) {
   MCAsmParser &Parser = getParser();
   StringRef IDVal = DirectiveID.getIdentifier();
+  if (IDVal.startswith(".arch"))
+    return parseDirectiveArch();
   if (IDVal.startswith(".code"))
     return ParseDirectiveCode(IDVal, DirectiveID.getLoc());
   else if (IDVal.startswith(".att_syntax")) {
@@ -4027,6 +4031,15 @@
   return true;
 }
 
+bool X86AsmParser::parseDirectiveArch() {
+  SMLoc Loc = getTok().getLoc();
+  StringRef CPU = getParser().parseStringToEndOfStatement().trim();
+  X86::CPUKind Kind = X86::parseArchX86(CPU);
+  if (Kind == X86::CK_None)
+    return Error(Loc, "unknown arch name");
+  return false;
+}
+
 /// parseDirectiveEven
 ///  ::= .even
 bool X86AsmParser::parseDirectiveEven(SMLoc L) {
diff --git a/llvm/test/MC/X86/directive-arch.s b/llvm/test/MC/X86/directive-arch.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/X86/directive-arch.s
@@ -0,0 +1,11 @@
+## We currently parse but ignore .arch directives.
+# RUN: llvm-mc -triple=x86_64 %s | FileCheck /dev/null --implicit-check-not=.arch
+# RUN: not llvm-mc -triple=x86_64 --defsym=ERR=1 %s 2>&1 | FileCheck %s --check-prefix=ERR
+
+.arch i386
+retq
+
+.ifdef ERR
+# ERR: {{.*}}.s:[[#@LINE+1]]:7: error: unknown arch name
+.arch unknown
+.endif