diff --git a/llvm/include/llvm/ADT/IndexedMap.h b/llvm/include/llvm/ADT/IndexedMap.h
index cda0316dc78fa..638fe14bfe797 100644
--- a/llvm/include/llvm/ADT/IndexedMap.h
+++ b/llvm/include/llvm/ADT/IndexedMap.h
@@ -22,12 +22,21 @@
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/identity.h"
 #include <cassert>
 
 namespace llvm {
 
-template <typename T, typename ToIndexT = identity<unsigned>> class IndexedMap {
+namespace detail {
+template <class Ty> struct IdentityIndex {
+  using argument_type = Ty;
+
+  Ty &operator()(Ty &self) const { return self; }
+  const Ty &operator()(const Ty &self) const { return self; }
+};
+} // namespace detail
+
+template <typename T, typename ToIndexT = detail::IdentityIndex<unsigned>>
+class IndexedMap {
   using IndexT = typename ToIndexT::argument_type;
   // Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
   // can grow very large and SmallVector grows more efficiently as long as T
diff --git a/llvm/include/llvm/ADT/identity.h b/llvm/include/llvm/ADT/identity.h
deleted file mode 100644
index 88d033fc01141..0000000000000
--- a/llvm/include/llvm/ADT/identity.h
+++ /dev/null
@@ -1,31 +0,0 @@
-//===- llvm/ADT/Identity.h - Provide std::identity from C++20 ---*- C++ -*-===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file provides an implementation of std::identity from C++20.
-//
-// No library is required when using these functions.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_ADT_IDENTITY_H
-#define LLVM_ADT_IDENTITY_H
-
-namespace llvm {
-
-// Similar to `std::identity` from C++20.
-template <class Ty> struct identity {
-  using is_transparent = void;
-  using argument_type = Ty;
-
-  Ty &operator()(Ty &self) const { return self; }
-  const Ty &operator()(const Ty &self) const { return self; }
-};
-
-} // namespace llvm
-
-#endif // LLVM_ADT_IDENTITY_H