Index: lib/MC/MCParser/AsmParser.cpp
===================================================================
--- lib/MC/MCParser/AsmParser.cpp
+++ lib/MC/MCParser/AsmParser.cpp
@@ -339,8 +339,8 @@
     DK_WEAK_DEF_CAN_BE_HIDDEN, DK_COMM, DK_COMMON, DK_LCOMM, DK_ABORT,
     DK_INCLUDE, DK_INCBIN, DK_CODE16, DK_CODE16GCC, DK_REPT, DK_IRP, DK_IRPC,
     DK_IF, DK_IFEQ, DK_IFGE, DK_IFGT, DK_IFLE, DK_IFLT, DK_IFNE, DK_IFB,
-    DK_IFNB, DK_IFC, DK_IFEQS, DK_IFNC, DK_IFDEF, DK_IFNDEF, DK_IFNOTDEF,
-    DK_ELSEIF, DK_ELSE, DK_ENDIF,
+    DK_IFNB, DK_IFC, DK_IFEQS, DK_IFNC, DK_IFNES, DK_IFDEF, DK_IFNDEF,
+    DK_IFNOTDEF, DK_ELSEIF, DK_ELSE, DK_ENDIF,
     DK_SPACE, DK_SKIP, DK_FILE, DK_LINE, DK_LOC, DK_STABS,
     DK_CFI_SECTIONS, DK_CFI_STARTPROC, DK_CFI_ENDPROC, DK_CFI_DEF_CFA,
     DK_CFI_DEF_CFA_OFFSET, DK_CFI_ADJUST_CFA_OFFSET, DK_CFI_DEF_CFA_REGISTER,
@@ -435,8 +435,8 @@
   bool parseDirectiveIfb(SMLoc DirectiveLoc, bool ExpectBlank);
   // ".ifc" or ".ifnc", depending on ExpectEqual.
   bool parseDirectiveIfc(SMLoc DirectiveLoc, bool ExpectEqual);
-  // ".ifeqs"
-  bool parseDirectiveIfeqs(SMLoc DirectiveLoc);
+  // ".ifeqs" or ".ifnes", depending on ExpectEqual.
+  bool parseDirectiveIfeqs(SMLoc DirectiveLoc, bool ExpectEqual);
   // ".ifdef" or ".ifndef", depending on expect_defined
   bool parseDirectiveIfdef(SMLoc DirectiveLoc, bool expect_defined);
   bool parseDirectiveElseIf(SMLoc DirectiveLoc); // ".elseif"
@@ -1244,9 +1244,11 @@
   case DK_IFC:
     return parseDirectiveIfc(IDLoc, true);
   case DK_IFEQS:
-    return parseDirectiveIfeqs(IDLoc);
+    return parseDirectiveIfeqs(IDLoc, true);
   case DK_IFNC:
     return parseDirectiveIfc(IDLoc, false);
+  case DK_IFNES:
+    return parseDirectiveIfeqs(IDLoc, false);
   case DK_IFDEF:
     return parseDirectiveIfdef(IDLoc, true);
   case DK_IFNDEF:
@@ -3923,14 +3925,18 @@
     StringRef Str1 = parseStringToComma();
 
     if (getLexer().isNot(AsmToken::Comma))
-      return TokError("unexpected token in '.ifc' directive");
+      return ExpectEqual ?
+             TokError("unexpected token in '.ifc' directive"):
+             TokError("unexpected token in '.ifnc' directive");
 
     Lex();
 
     StringRef Str2 = parseStringToEndOfStatement();
 
     if (getLexer().isNot(AsmToken::EndOfStatement))
-      return TokError("unexpected token in '.ifc' directive");
+      return ExpectEqual ?
+             TokError("unexpected token in '.ifc' directive"):
+             TokError("unexpected token in '.ifnc' directive");
 
     Lex();
 
@@ -3943,9 +3949,12 @@
 
 /// parseDirectiveIfeqs
 ///   ::= .ifeqs string1, string2
-bool AsmParser::parseDirectiveIfeqs(SMLoc DirectiveLoc) {
+bool AsmParser::parseDirectiveIfeqs(SMLoc DirectiveLoc, bool ExpectEqual) {
   if (Lexer.isNot(AsmToken::String)) {
-    TokError("expected string parameter for '.ifeqs' directive");
+    if (ExpectEqual)
+      TokError("expected string parameter for '.ifeqs' directive");
+    else
+      TokError("expected string parameter for '.ifnes' directive");
     eatToEndOfStatement();
     return true;
   }
@@ -3954,7 +3963,10 @@
   Lex();
 
   if (Lexer.isNot(AsmToken::Comma)) {
-    TokError("expected comma after first string for '.ifeqs' directive");
+    if (ExpectEqual)
+      TokError("expected comma after first string for '.ifeqs' directive");
+    else
+      TokError("expected comma after first string for '.ifnes' directive");
     eatToEndOfStatement();
     return true;
   }
@@ -3962,7 +3974,10 @@
   Lex();
 
   if (Lexer.isNot(AsmToken::String)) {
-    TokError("expected string parameter for '.ifeqs' directive");
+    if (ExpectEqual)
+      TokError("expected string parameter for '.ifeqs' directive");
+    else
+      TokError("expected string parameter for '.ifnes' directive");
     eatToEndOfStatement();
     return true;
   }
@@ -3972,7 +3987,7 @@
 
   TheCondStack.push_back(TheCondState);
   TheCondState.TheCond = AsmCond::IfCond;
-  TheCondState.CondMet = String1 == String2;
+  TheCondState.CondMet = ExpectEqual == (String1 == String2);
   TheCondState.Ignore = !TheCondState.CondMet;
 
   return false;
@@ -4219,6 +4234,7 @@
   DirectiveKindMap[".ifc"] = DK_IFC;
   DirectiveKindMap[".ifeqs"] = DK_IFEQS;
   DirectiveKindMap[".ifnc"] = DK_IFNC;
+  DirectiveKindMap[".ifnes"] = DK_IFNES;
   DirectiveKindMap[".ifdef"] = DK_IFDEF;
   DirectiveKindMap[".ifndef"] = DK_IFNDEF;
   DirectiveKindMap[".ifnotdef"] = DK_IFNOTDEF;
Index: test/MC/AsmParser/ifeqs-diagnostics.s
===================================================================
--- test/MC/AsmParser/ifeqs-diagnostics.s
+++ test/MC/AsmParser/ifeqs-diagnostics.s
@@ -20,3 +20,20 @@
 
 // CHECK-NOT: error: unmatched .ifs or .elses
 
+.ifnes
+
+// CHECK: error: expected string parameter for '.ifnes' directive
+// CHECK: .ifnes
+// CHECK:       ^
+
+.ifnes "string1"
+
+// CHECK: error: expected comma after first string for '.ifnes' directive
+// CHECK: .ifnes "string1"
+// CHECK:                 ^
+
+.ifnes "string1",
+
+// CHECK: error: expected string parameter for '.ifnes' directive
+// CHECK: .ifnes "string1",
+// CHECK:                  ^
Index: test/MC/AsmParser/ifnes.s
===================================================================
--- /dev/null
+++ test/MC/AsmParser/ifnes.s
@@ -0,0 +1,22 @@
+# RUN: llvm-mc -triple i386-unknown-unknown %s | FileCheck %s
+
+# CHECK-NOT: .byte 0
+# CHECK: .byte 1
+.ifnes "foo space", "foo space"
+	.byte 0
+.else
+	.byte 1
+.endif
+
+# CHECK-NOT: .byte 0
+# CHECK: .byte 1
+.ifnes "unequal", "unEqual"
+	.byte 1
+.else
+	.byte 0
+.endif
+
+# CHECK-NOT: .byte 0
+# CHECK: .byte 1
+.ifnes "equal", "equal" ; .byte 0 ; .else ; .byte 1 ; .endif
+