Index: llvm/lib/Passes/PassBuilderPipelines.cpp
===================================================================
--- llvm/lib/Passes/PassBuilderPipelines.cpp
+++ llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -832,7 +832,7 @@
     C(MPM, Level);
 
   // Specialize functions with IPSCCP.
-  if (EnableFunctionSpecialization)
+  if (EnableFunctionSpecialization && Level == OptimizationLevel::O3)
     MPM.addPass(FunctionSpecializationPass());
 
   // Interprocedural constant propagation now that basic cleanup has occurred
@@ -1399,7 +1399,7 @@
     MPM.addPass(PGOIndirectCallPromotion(
         true /* InLTO */, PGOOpt && PGOOpt->Action == PGOOptions::SampleUse));
 
-    if (EnableFunctionSpecialization)
+    if (EnableFunctionSpecialization && Level.getSpeedupLevel() > 2)
       MPM.addPass(FunctionSpecializationPass());
     // Propagate constants at call sites into the functions they call.  This
     // opens opportunities for globalopt (and inlining) by substituting function
Index: llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
===================================================================
--- llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -1017,7 +1017,7 @@
         createPGOIndirectCallPromotionLegacyPass(true, !PGOSampleUse.empty()));
 
     // Propage constant function arguments by specializing the functions.
-    if (EnableFunctionSpecialization)
+    if (EnableFunctionSpecialization && OptLevel > 2)
       PM.add(createFunctionSpecializationPass());
 
     // Propagate constants at call sites into the functions they call.  This