diff --git a/llvm/test/tools/llvm-cxxfilt/delimiters.test b/llvm/test/tools/llvm-cxxfilt/delimiters.test
--- a/llvm/test/tools/llvm-cxxfilt/delimiters.test
+++ b/llvm/test/tools/llvm-cxxfilt/delimiters.test
@@ -27,6 +27,7 @@
 RUN:      '_Z3Foo|'   \
 RUN:      '_Z3Foo}'   \
 RUN:      '_Z3Foo~,,' \
+RUN:      '_Z3Foo⦙_Z3Bar' \
 RUN:      '_Z3Foo,,_Z3Bar::_Z3Baz  _Z3Foo,_Z3Bar:_Z3Baz' \
 RUN:      '_Z3Foo$ ._Z3Foo' | llvm-cxxfilt -n | FileCheck %s
 
@@ -59,5 +60,6 @@
 CHECK: Foo|
 CHECK: Foo}
 CHECK: Foo~,,
+CHECK: Foo⦙Bar
 CHECK: Foo,,Bar::Baz  Foo,Bar:Baz
 CHECK: _Z3Foo$ ._Z3Foo
diff --git a/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
--- a/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
+++ b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
@@ -128,7 +128,7 @@
 static bool IsLegalItaniumChar(char C) {
   // Itanium CXX ABI [External Names]p5.1.1:
   // '$' and '.' in mangled names are reserved for private implementations.
-  return isalnum(C) || C == '.' || C == '$' || C == '_';
+  return isAlnum(C) || C == '.' || C == '$' || C == '_';
 }
 
 // If 'Split' is true, then 'Mangled' is broken into individual words and each