Index: llvm/include/llvm/InitializePasses.h
===================================================================
--- llvm/include/llvm/InitializePasses.h
+++ llvm/include/llvm/InitializePasses.h
@@ -288,7 +288,7 @@
 void initializeMemorySSAPrinterLegacyPassPass(PassRegistry&);
 void initializeMemorySSAWrapperPassPass(PassRegistry&);
 void initializeMemorySanitizerLegacyPassPass(PassRegistry&);
-void initializeMergeFunctionsPass(PassRegistry&);
+void initializeMergeFunctionsLegacyPassPass(PassRegistry&);
 void initializeMergeICmpsLegacyPassPass(PassRegistry &);
 void initializeMergedLoadStoreMotionLegacyPassPass(PassRegistry&);
 void initializeMetaRenamerPass(PassRegistry&);
Index: llvm/include/llvm/Transforms/IPO/MergeFunctions.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Transforms/IPO/MergeFunctions.h
@@ -0,0 +1,32 @@
+//===- MergeFunctions.h - Merge Identical Functions -------------*- 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 pass transforms simple global variables that never have their address
+// taken.  If obviously true, it marks read/write globals as constant, deletes
+// variables only stored to, etc.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_IPO_MERGEFUNCTIONS_H
+#define LLVM_TRANSFORMS_IPO_MERGEFUNCTIONS_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class Module;
+
+/// Merge identical functions.
+class MergeFunctionsPass : public PassInfoMixin<MergeFunctionsPass> {
+public:
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_IPO_MERGEFUNCTIONS_H
Index: llvm/lib/Passes/PassBuilder.cpp
===================================================================
--- llvm/lib/Passes/PassBuilder.cpp
+++ llvm/lib/Passes/PassBuilder.cpp
@@ -86,6 +86,7 @@
 #include "llvm/Transforms/IPO/Inliner.h"
 #include "llvm/Transforms/IPO/Internalize.h"
 #include "llvm/Transforms/IPO/LowerTypeTests.h"
+#include "llvm/Transforms/IPO/MergeFunctions.h"
 #include "llvm/Transforms/IPO/PartialInlining.h"
 #include "llvm/Transforms/IPO/SCCP.h"
 #include "llvm/Transforms/IPO/SampleProfile.h"
Index: llvm/lib/Passes/PassRegistry.def
===================================================================
--- llvm/lib/Passes/PassRegistry.def
+++ llvm/lib/Passes/PassRegistry.def
@@ -64,6 +64,7 @@
 MODULE_PASS("invalidate<all>", InvalidateAllAnalysesPass())
 MODULE_PASS("ipsccp", IPSCCPPass())
 MODULE_PASS("lowertypetests", LowerTypeTestsPass(nullptr, nullptr))
+MODULE_PASS("mergefunc", MergeFunctionsPass())
 MODULE_PASS("name-anon-globals", NameAnonGlobalPass())
 MODULE_PASS("no-op-module", NoOpModulePass())
 MODULE_PASS("partial-inliner", PartialInlinerPass())
Index: llvm/lib/Transforms/IPO/IPO.cpp
===================================================================
--- llvm/lib/Transforms/IPO/IPO.cpp
+++ llvm/lib/Transforms/IPO/IPO.cpp
@@ -43,7 +43,7 @@
   initializeBlockExtractorPass(Registry);
   initializeSingleLoopExtractorPass(Registry);
   initializeLowerTypeTestsPass(Registry);
-  initializeMergeFunctionsPass(Registry);
+  initializeMergeFunctionsLegacyPassPass(Registry);
   initializePartialInlinerLegacyPassPass(Registry);
   initializeAttributorLegacyPassPass(Registry);
   initializePostOrderFunctionAttrsLegacyPassPass(Registry);
Index: llvm/lib/Transforms/IPO/MergeFunctions.cpp
===================================================================
--- llvm/lib/Transforms/IPO/MergeFunctions.cpp
+++ llvm/lib/Transforms/IPO/MergeFunctions.cpp
@@ -122,6 +122,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/MergeFunctions.h"
 #include "llvm/Transforms/Utils/FunctionComparator.h"
 #include <algorithm>
 #include <cassert>
@@ -196,16 +197,12 @@
 /// by considering all pointer types to be equivalent. Once identified,
 /// MergeFunctions will fold them by replacing a call to one to a call to a
 /// bitcast of the other.
-class MergeFunctions : public ModulePass {
+class MergeFunctions {
 public:
-  static char ID;
-
-  MergeFunctions()
-    : ModulePass(ID), FnTree(FunctionNodeCmp(&GlobalNumbers)) {
-    initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
+  MergeFunctions() : FnTree(FunctionNodeCmp(&GlobalNumbers)) {
   }
 
-  bool runOnModule(Module &M) override;
+  bool runOnModule(Module &M);
 
 private:
   // The function comparison operator is provided here so that FunctionNodes do
@@ -298,14 +295,39 @@
   DenseMap<AssertingVH<Function>, FnTreeType::iterator> FNodesInTree;
 };
 
-} // end anonymous namespace
+class MergeFunctionsLegacyPass : public ModulePass {
+public:
+  static char ID;
 
-char MergeFunctions::ID = 0;
+  MergeFunctionsLegacyPass(): ModulePass(ID) {
+    initializeMergeFunctionsLegacyPassPass(*PassRegistry::getPassRegistry());
+  }
 
-INITIALIZE_PASS(MergeFunctions, "mergefunc", "Merge Functions", false, false)
+  bool runOnModule(Module &M) override {
+    if (skipModule(M))
+      return false;
+
+    MergeFunctions MF;
+    return MF.runOnModule(M);
+  }
+};
+
+} // end anonymous namespace
+
+char MergeFunctionsLegacyPass::ID = 0;
+INITIALIZE_PASS(MergeFunctionsLegacyPass, "mergefunc",
+                "Merge Functions", false, false)
 
 ModulePass *llvm::createMergeFunctionsPass() {
-  return new MergeFunctions();
+  return new MergeFunctionsLegacyPass();
+}
+
+PreservedAnalyses MergeFunctionsPass::run(Module &M,
+                                          ModuleAnalysisManager &AM) {
+  MergeFunctions MF;
+  if (!MF.runOnModule(M))
+    return PreservedAnalyses::all();
+  return PreservedAnalyses::none();
 }
 
 #ifndef NDEBUG
@@ -387,9 +409,6 @@
 }
 
 bool MergeFunctions::runOnModule(Module &M) {
-  if (skipModule(M))
-    return false;
-
   bool Changed = false;
 
   // All functions in the module, ordered by hash. Functions with a unique
Index: llvm/test/Transforms/MergeFunc/merge-block-address.ll
===================================================================
--- llvm/test/Transforms/MergeFunc/merge-block-address.ll
+++ llvm/test/Transforms/MergeFunc/merge-block-address.ll
@@ -1,4 +1,5 @@
 ; RUN: opt -S -mergefunc < %s | FileCheck %s
+; RUN: opt -S -passes=mergefunc < %s | FileCheck %s
 
 ; These two functions are identical. The basic block labels are the same, and
 ; induce the same CFG. We are testing that block addresses within different