diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 4b7c7f07fed990..bf3061ad541e34 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -2528,6 +2528,8 @@ bool AsmParser::expandMacro(raw_svector_ostream &OS, MCAsmMacro &Macro,
       while (I != End && isIdentifierChar(Body[I]))
         ++I;
       StringRef Argument(Body.data() + Pos, I - Pos);
+      if (AltMacroMode && I != End && Body[I] == '&')
+        ++I;
       unsigned Index = 0;
       for (; Index < NParameters; ++Index)
         if (Parameters[Index].Name == Argument)
diff --git a/llvm/test/MC/AsmParser/altmacro_expression.s b/llvm/test/MC/AsmParser/altmacro_expression.s
index 58d8b486cf85dd..cee0a6872541a9 100644
--- a/llvm/test/MC/AsmParser/altmacro_expression.s
+++ b/llvm/test/MC/AsmParser/altmacro_expression.s
@@ -3,10 +3,12 @@
 # Checking that the '%' was evaluated as a string first
 # In a fail scenario: The asmprint will print: addl $%(1+4), %eax
 
-# CHECK:  addl $5, %eax
+# CHECK:       addl $5, %eax
+# CHECK-NEXT:  addl $5, %eax
 .altmacro
 .macro percent_expr arg
     addl $\arg, %eax
+    addl $\arg&, %eax
 .endm
 
 percent_expr %(1+4)