diff --git a/lib/MC/MCParser/AsmLexer.cpp b/lib/MC/MCParser/AsmLexer.cpp
index b49dd010479..a066e648303 100644
--- a/lib/MC/MCParser/AsmLexer.cpp
+++ b/lib/MC/MCParser/AsmLexer.cpp
@@ -139,20 +139,23 @@ AsmToken AsmLexer::LexHexFloatLiteral(bool NoIntDigits) {
 }
 
 /// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@?]*
-static bool IsIdentifierChar(char c) {
-  return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@' || c == '?';
+static bool IsIdentifierChar(char c, bool AllowAt) {
+  return isalnum(c) || c == '_' || c == '$' || c == '.' ||
+         (c == '@' && AllowAt) || c == '?';
 }
 AsmToken AsmLexer::LexIdentifier() {
+  bool AllowAtInIdentifier = !StringRef(MAI.getCommentString()).startswith("@");
   // Check for floating point literals.
   if (CurPtr[-1] == '.' && isdigit(*CurPtr)) {
     // Disambiguate a .1243foo identifier from a floating literal.
     while (isdigit(*CurPtr))
       ++CurPtr;
-    if (*CurPtr == 'e' || *CurPtr == 'E' || !IsIdentifierChar(*CurPtr))
+    if (*CurPtr == 'e' || *CurPtr == 'E' ||
+        !IsIdentifierChar(*CurPtr, AllowAtInIdentifier))
       return LexFloatLiteral();
   }
 
-  while (IsIdentifierChar(*CurPtr))
+  while (IsIdentifierChar(*CurPtr, AllowAtInIdentifier))
     ++CurPtr;
 
   // Handle . as a special case.
diff --git a/test/MC/ARM/comment.s b/test/MC/ARM/comment.s
new file mode 100644
index 00000000000..e95f313aca2
--- /dev/null
+++ b/test/MC/ARM/comment.s
@@ -0,0 +1,24 @@
+@ Tests to check that '@' does not get lexed as an identifier for arm
+@ RUN: llvm-mc %s -triple=armv7-linux-gnueabi  | FileCheck %s
+@ RUN: llvm-mc %s -triple=armv7-linux-gnueabi 2>&1 | FileCheck %s --check-prefix=ERROR
+
+foo:
+  bl boo@plt should be ignored
+  bl goo@plt
+  .long bar@got to parse this as a comment
+  .long baz@got
+  add r0, r0@ignore this extra junk
+
+@CHECK-LABEL: foo:
+@CHECK: bl boo
+@CHECK-NOT: @
+@CHECK: bl goo
+@CHECK-NOT: @
+@CHECK: .long bar
+@CHECK-NOT: @
+@CHECK: .long baz
+@CHECK-NOT: @
+@CHECK: add r0, r0
+@CHECK-NOT: @
+
+@ERROR-NOT: error: