diff --git a/clang/tools/clang-fuzzer/handle-llvm/handle_llvm.cpp b/clang/tools/clang-fuzzer/handle-llvm/handle_llvm.cpp
--- a/clang/tools/clang-fuzzer/handle-llvm/handle_llvm.cpp
+++ b/clang/tools/clang-fuzzer/handle-llvm/handle_llvm.cpp
@@ -30,34 +30,28 @@
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LLVMContext.h"
-#include "llvm/IR/LegacyPassManager.h"
-#include "llvm/IR/LegacyPassNameParser.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Verifier.h"
+#include "llvm/IRPrinter/IRPrintingPasses.h"
 #include "llvm/IRReader/IRReader.h"
 #include "llvm/MC/TargetRegistry.h"
-#include "llvm/Pass.h"
-#include "llvm/PassRegistry.h"
+#include "llvm/Passes/OptimizationLevel.h"
+#include "llvm/Passes/PassBuilder.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Target/TargetMachine.h"
-#include "llvm/Transforms/IPO.h"
-#include "llvm/Transforms/IPO/PassManagerBuilder.h"
-#include "llvm/Transforms/Vectorize.h"
 
 using namespace llvm;
 
-static codegen::RegisterCodeGenFlags CGF;
-
 // Define a type for the functions that are compiled and executed
 typedef void (*LLVMFunc)(int*, int*, int*, int);
 
 // Helper function to parse command line args and find the optimization level
-static void getOptLevel(const std::vector<const char *> &ExtraArgs,
-                              CodeGenOpt::Level &OLvl) {
+static CodeGenOpt::Level
+getOptLevel(const std::vector<const char *> &ExtraArgs) {
   // Find the optimization level from the command line args
-  OLvl = CodeGenOpt::Default;
+  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
   for (auto &A : ExtraArgs) {
     if (A[0] == '-' && A[1] == 'O') {
       switch(A[2]) {
@@ -71,6 +65,7 @@
       }
     }
   }
+  return OLvl;
 }
 
 static void ErrorAndExit(std::string message) {
@@ -80,16 +75,45 @@
 
 // Helper function to add optimization passes to the TargetMachine at the 
 // specified optimization level, OptLevel
-static void AddOptimizationPasses(legacy::PassManagerBase &MPM,
-                                  CodeGenOpt::Level OptLevel,
-                                  unsigned SizeLevel) {
-  // Create and initialize a PassManagerBuilder
-  PassManagerBuilder Builder;
-  Builder.OptLevel = OptLevel;
-  Builder.SizeLevel = SizeLevel;
-  Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel, false);
-  Builder.LoopVectorize = true;
-  Builder.populateModulePassManager(MPM);
+static void RunOptimizationPasses(raw_ostream &OS, Module &M,
+                                  CodeGenOpt::Level OptLevel) {
+  llvm::OptimizationLevel OL;
+  switch (OptLevel) {
+  case CodeGenOpt::None:
+    OL = OptimizationLevel::O0;
+    break;
+  case CodeGenOpt::Less:
+    OL = OptimizationLevel::O1;
+    break;
+  case CodeGenOpt::Default:
+    OL = OptimizationLevel::O2;
+    break;
+  case CodeGenOpt::Aggressive:
+    OL = OptimizationLevel::O3;
+    break;
+  }
+
+  LoopAnalysisManager LAM;
+  FunctionAnalysisManager FAM;
+  CGSCCAnalysisManager CGAM;
+  ModuleAnalysisManager MAM;
+
+  PassBuilder PB;
+
+  PB.registerModuleAnalyses(MAM);
+  PB.registerCGSCCAnalyses(CGAM);
+  PB.registerFunctionAnalyses(FAM);
+  PB.registerLoopAnalyses(LAM);
+  PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
+
+  ModulePassManager MPM;
+  if (OL == OptimizationLevel::O0)
+    MPM = PB.buildO0DefaultPipeline(OL);
+  else
+    MPM = PB.buildPerModuleDefaultPipeline(OL);
+  MPM.addPass(PrintModulePass(OS));
+
+  MPM.run(M, MAM);
 }
 
 // Mimics the opt tool to run an optimization pass over the provided IR
@@ -120,24 +144,10 @@
   codegen::setFunctionAttributes(codegen::getCPUStr(),
                                  codegen::getFeaturesStr(), *M);
 
-  legacy::PassManager Passes;
-  
-  Passes.add(new TargetLibraryInfoWrapperPass(ModuleTriple));
-  Passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
-
-  LLVMTargetMachine &LTM = static_cast<LLVMTargetMachine &>(*TM);
-  Passes.add(LTM.createPassConfig(Passes));
-
-  Passes.add(createVerifierPass());
-
-  AddOptimizationPasses(Passes, OLvl, 0);
-
   // Add a pass that writes the optimized IR to an output stream
   std::string outString;
   raw_string_ostream OS(outString);
-  Passes.add(createPrintModulePass(OS, "", false));
-
-  Passes.run(*M);
+  RunOptimizationPasses(OS, *M, OLvl);
 
   return outString;
 }
@@ -216,8 +226,7 @@
   memcpy(UnoptArrays, InputArrays, kTotalSize);
 
   // Parse ExtraArgs to set the optimization level
-  CodeGenOpt::Level OLvl;
-  getOptLevel(ExtraArgs, OLvl);
+  CodeGenOpt::Level OLvl = getOptLevel(ExtraArgs);
 
   // First we optimize the IR by running a loop vectorizer pass
   std::string OptIR = OptLLVM(IR, OLvl);