diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 09950e8f6666..204ccf77a758 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -588,7 +588,7 @@ X86Operand *X86ATTAsmParser::ParseMemOperand(unsigned SegReg, SMLoc MemStart) {
         }
       }
     } else if (getLexer().isNot(AsmToken::RParen)) {
-      // Otherwise we have the unsupported form of a scale amount without an
+      // A scale amount without an index is ignored.
       // index.
       SMLoc Loc = Parser.getTok().getLoc();
 
@@ -596,8 +596,9 @@ X86Operand *X86ATTAsmParser::ParseMemOperand(unsigned SegReg, SMLoc MemStart) {
       if (getParser().ParseAbsoluteExpression(Value))
         return 0;
 
-      Error(Loc, "cannot have scale factor without index register");
-      return 0;
+      if (Value != 1)
+        Warning(Loc, "scale factor without index register is ignored");
+      Scale = 1;
     }
   }
 
diff --git a/llvm/test/MC/AsmParser/X86/x86_instructions.s b/llvm/test/MC/AsmParser/X86/x86_instructions.s
index 92fb1b243114..8adcc9e0cdf0 100644
--- a/llvm/test/MC/AsmParser/X86/x86_instructions.s
+++ b/llvm/test/MC/AsmParser/X86/x86_instructions.s
@@ -1,4 +1,6 @@
-// RUN: llvm-mc -triple x86_64-unknown-unknown %s | FileCheck %s
+// RUN: llvm-mc -triple x86_64-unknown-unknown %s > %t 2> %t.err
+// RUN: FileCheck < %t %s
+// RUN: FileCheck --check-prefix=CHECK-STDERR < %t.err %s
 
 // CHECK: subb %al, %al
         subb %al, %al
@@ -151,3 +153,8 @@ fadd %st(7)
 // CHECK: int3
 INT3
 
+
+// Allow scale factor without index register.
+// CHECK: movaps	%xmm3, (%esi)
+// CHECK-STDERR: warning: scale factor without index register is ignored
+movaps %xmm3, (%esi, 2)