diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
--- a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -245,6 +245,10 @@
                                        FunctionAnalysisManager &AM) {
   auto &TTI = AM.getResult<TargetIRAnalysis>(F);
   Options.AC = &AM.getResult<AssumptionAnalysis>(F);
+  if (F.hasFnAttribute(Attribute::OptForFuzzing))
+    Options.setSimplifyCondBranch(false).setFoldTwoEntryPHINode(false);
+  else
+    Options.setSimplifyCondBranch(true).setFoldTwoEntryPHINode(true);
   if (!simplifyFunctionCFG(F, TTI, Options))
     return PreservedAnalyses::all();
   PreservedAnalyses PA;
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2415,6 +2415,9 @@
   // dependence information for this check, but simplifycfg can't keep it up
   // to date, and this catches most of the cases we care about anyway.
   BasicBlock *BB = PN->getParent();
+  const Function *Fn = BB->getParent();
+  if (Fn && Fn->hasFnAttribute(Attribute::OptForFuzzing))
+    return false;
 
   BasicBlock *IfTrue, *IfFalse;
   Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse);
@@ -6055,7 +6058,9 @@
 
 bool SimplifyCFGOpt::simplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) {
   BasicBlock *BB = BI->getParent();
-  if (!Options.SimplifyCondBranch)
+  const Function *Fn = BB->getParent();
+  if (Fn && Fn->hasFnAttribute(Attribute::OptForFuzzing) &&
+      !Options.SimplifyCondBranch)
     return false;
 
   // Conditional branch
diff --git a/llvm/test/Transforms/SimplifyCFG/opt-for-fuzzing.ll b/llvm/test/Transforms/SimplifyCFG/opt-for-fuzzing.ll
--- a/llvm/test/Transforms/SimplifyCFG/opt-for-fuzzing.ll
+++ b/llvm/test/Transforms/SimplifyCFG/opt-for-fuzzing.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -passes=simplifycfg -S | FileCheck %s
 
 define i32 @foo(i32 %x) optforfuzzing {
 entry: