diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp
--- a/llvm/lib/MC/MCAsmInfo.cpp
+++ b/llvm/lib/MC/MCAsmInfo.cpp
@@ -114,7 +114,10 @@
 }
 
 bool MCAsmInfo::isAcceptableChar(char C) const {
-  return isAlnum(C) || C == '_' || C == '$' || C == '.' || C == '@';
+  if (C == '@')
+    return doesAllowAtInName();
+
+  return isAlnum(C) || C == '_' || C == '$' || C == '.';
 }
 
 bool MCAsmInfo::isValidUnquotedName(StringRef Name) const {
diff --git a/llvm/test/CodeGen/AArch64/ehcontguard.ll b/llvm/test/CodeGen/AArch64/ehcontguard.ll
--- a/llvm/test/CodeGen/AArch64/ehcontguard.ll
+++ b/llvm/test/CodeGen/AArch64/ehcontguard.ll
@@ -1,7 +1,7 @@
 ; RUN: llc < %s -mtriple=aarch64-windows | FileCheck %s
 ; EHCont Guard is currently only available on Windows
 
-; CHECK: .set @feat.00, 16384
+; CHECK: .set "@feat.00", 16384
 
 ; CHECK: .section .gehcont$y
 
diff --git a/llvm/test/CodeGen/AArch64/win_cst_pool.ll b/llvm/test/CodeGen/AArch64/win_cst_pool.ll
--- a/llvm/test/CodeGen/AArch64/win_cst_pool.ll
+++ b/llvm/test/CodeGen/AArch64/win_cst_pool.ll
@@ -4,14 +4,14 @@
 define double @double() {
   ret double 0x2000000000800001
 }
-; CHECK:              .globl  __real@2000000000800001
-; CHECK-NEXT:         .section        .rdata,"dr",discard,__real@2000000000800001
+; CHECK:              .globl "__real@2000000000800001"
+; CHECK-NEXT:         .section        .rdata,"dr",discard,"__real@2000000000800001"
 ; CHECK-NEXT:         .p2align  3
-; CHECK-NEXT: __real@2000000000800001:
+; CHECK-NEXT: "__real@2000000000800001":
 ; CHECK-NEXT:         .xword   0x2000000000800001
 ; CHECK:      double:
-; CHECK:               adrp    x8, __real@2000000000800001
-; CHECK-NEXT:          ldr     d0, [x8, :lo12:__real@2000000000800001]
+; CHECK:               adrp    x8, "__real@2000000000800001"
+; CHECK-NEXT:          ldr     d0, [x8, :lo12:"__real@2000000000800001"]
 ; CHECK-NEXT:          ret
 
 ; MINGW:              .section        .rdata,"dr"
diff --git a/llvm/unittests/MC/SystemZ/SystemZAsmLexerTest.cpp b/llvm/unittests/MC/SystemZ/SystemZAsmLexerTest.cpp
--- a/llvm/unittests/MC/SystemZ/SystemZAsmLexerTest.cpp
+++ b/llvm/unittests/MC/SystemZ/SystemZAsmLexerTest.cpp
@@ -554,9 +554,11 @@
 }
 
 TEST_F(SystemZAsmLexerLinux, CheckPrintAcceptableSymbol) {
-  std::string AsmStr = "ab13_$.@";
+  std::string AsmStr = "ab13_$.";
   EXPECT_EQ(true, MAI->isValidUnquotedName(AsmStr));
-  AsmStr += "#";
+  AsmStr = "ab13_$.@";
+  EXPECT_EQ(false, MAI->isValidUnquotedName(AsmStr));
+  AsmStr = "ab13_$.#";
   EXPECT_EQ(false, MAI->isValidUnquotedName(AsmStr));
 }