diff --git a/llvm/include/llvm/Transforms/Utils/Cloning.h b/llvm/include/llvm/Transforms/Utils/Cloning.h
--- a/llvm/include/llvm/Transforms/Utils/Cloning.h
+++ b/llvm/include/llvm/Transforms/Utils/Cloning.h
@@ -260,10 +260,14 @@
 /// and all varargs at the callsite will be passed to any calls to
 /// ForwardVarArgsTo. The caller of InlineFunction has to make sure any varargs
 /// are only used by ForwardVarArgsTo.
+///
+/// The callee's function attributes are merged into the callers' if
+/// MergeAttributes is set to true.
 InlineResult InlineFunction(CallBase &CB, InlineFunctionInfo &IFI,
                             AAResults *CalleeAAR = nullptr,
                             bool InsertLifetime = true,
-                            Function *ForwardVarArgsTo = nullptr);
+                            Function *ForwardVarArgsTo = nullptr,
+                            bool MergeAttributes = false);
 
 /// Clones a loop \p OrigLoop.  Returns the loop and the blocks in \p
 /// Blocks.
diff --git a/llvm/lib/Transforms/IPO/AlwaysInliner.cpp b/llvm/lib/Transforms/IPO/AlwaysInliner.cpp
--- a/llvm/lib/Transforms/IPO/AlwaysInliner.cpp
+++ b/llvm/lib/Transforms/IPO/AlwaysInliner.cpp
@@ -71,7 +71,9 @@
             &FAM.getResult<BlockFrequencyAnalysis>(F));
 
         InlineResult Res = InlineFunction(
-            *CB, IFI, &FAM.getResult<AAManager>(F), InsertLifetime);
+            *CB, IFI, &FAM.getResult<AAManager>(F), InsertLifetime,
+            /*ForwardVarArgsTo=*/nullptr,
+            /*MergeAttributes=*/true);
         if (!Res.isSuccess()) {
           ORE.emit([&]() {
             return OptimizationRemarkMissed(DEBUG_TYPE, "NotInlined", DLoc,
@@ -88,9 +90,6 @@
             InlineCost::getAlways("always inline attribute"),
             /*ForProfileContext=*/false, DEBUG_TYPE);
 
-        // Merge the attributes based on the inlining.
-        AttributeFuncs::mergeAttributesForInlining(*Caller, F);
-
         Changed = true;
       }
 
diff --git a/llvm/lib/Transforms/IPO/Inliner.cpp b/llvm/lib/Transforms/IPO/Inliner.cpp
--- a/llvm/lib/Transforms/IPO/Inliner.cpp
+++ b/llvm/lib/Transforms/IPO/Inliner.cpp
@@ -315,15 +315,15 @@
 
   // Try to inline the function.  Get the list of static allocas that were
   // inlined.
-  InlineResult IR = InlineFunction(CB, IFI, &AAR, InsertLifetime);
+  InlineResult IR = InlineFunction(CB, IFI, &AAR, InsertLifetime,
+                                   /*ForwardVarArgsTo=*/nullptr,
+                                   /*MergeAttributes=*/true);
   if (!IR.isSuccess())
     return IR;
 
   if (InlinerFunctionImportStats != InlinerFunctionImportStatsOpts::No)
     ImportedFunctionsStats.recordInline(*Caller, *Callee);
 
-  AttributeFuncs::mergeAttributesForInlining(*Caller, *Callee);
-
   if (!DisableInlinedAllocaMerging)
     mergeInlinedArrayAllocas(Caller, IFI, InlinedArrayAllocas, InlineHistory);
 
@@ -915,7 +915,10 @@
           &FAM.getResult<BlockFrequencyAnalysis>(Callee));
 
       InlineResult IR =
-          InlineFunction(*CB, IFI, &FAM.getResult<AAManager>(*CB->getCaller()));
+          InlineFunction(*CB, IFI, &FAM.getResult<AAManager>(*CB->getCaller()),
+                         /*InsertLifetime=*/true,
+                         /*ForwardVarArgsTo=*/nullptr,
+                         /*MergeAttributes=*/true);
       if (!IR.isSuccess()) {
         Advice->recordUnsuccessfulInlining(IR);
         continue;
@@ -970,9 +973,6 @@
         }
       }
 
-      // Merge the attributes based on the inlining.
-      AttributeFuncs::mergeAttributesForInlining(F, Callee);
-
       // For local functions or discardable functions without comdats, check
       // whether this makes the callee trivially dead. In that case, we can drop
       // the body of the function eagerly which may reduce the number of callers
diff --git a/llvm/lib/Transforms/IPO/ModuleInliner.cpp b/llvm/lib/Transforms/IPO/ModuleInliner.cpp
--- a/llvm/lib/Transforms/IPO/ModuleInliner.cpp
+++ b/llvm/lib/Transforms/IPO/ModuleInliner.cpp
@@ -218,7 +218,10 @@
         &FAM.getResult<BlockFrequencyAnalysis>(Callee));
 
     InlineResult IR =
-        InlineFunction(*CB, IFI, &FAM.getResult<AAManager>(*CB->getCaller()));
+        InlineFunction(*CB, IFI, &FAM.getResult<AAManager>(*CB->getCaller()),
+                       /*InsertLifetime=*/true,
+                       /*ForwardVarArgsTo=*/nullptr,
+                       /*MergeAttributes=*/true);
     if (!IR.isSuccess()) {
       Advice->recordUnsuccessfulInlining(IR);
       continue;
@@ -251,9 +254,6 @@
       }
     }
 
-    // Merge the attributes based on the inlining.
-    AttributeFuncs::mergeAttributesForInlining(F, Callee);
-
     // For local functions, check whether this makes the callee trivially
     // dead. In that case, we can drop the body of the function eagerly
     // which may reduce the number of callers of other functions to one,
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1221,13 +1221,14 @@
 
   InlineFunctionInfo IFI(nullptr, GetAC);
   IFI.UpdateProfile = false;
-  if (!InlineFunction(CB, IFI).isSuccess())
+  InlineResult IR = InlineFunction(CB, IFI,
+                                   /*CalleeAAR=*/nullptr,
+                                   /*InsertLifetime=*/true,
+                                   /*ForwardVarArgsTo=*/nullptr,
+                                   /*MergeAttributes=*/true);
+  if (!IR.isSuccess())
     return false;
 
-  // Merge the attributes based on the inlining.
-  AttributeFuncs::mergeAttributesForInlining(*BB->getParent(),
-                                             *CalledFunction);
-
   // The call to InlineFunction erases I, so we can't pass it here.
   emitInlinedIntoBasedOnCost(*ORE, DLoc, BB, *CalledFunction, *BB->getParent(),
                              Cost, true, getAnnotatedRemarkPassName());
diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -1786,7 +1786,8 @@
 llvm::InlineResult llvm::InlineFunction(CallBase &CB, InlineFunctionInfo &IFI,
                                         AAResults *CalleeAAR,
                                         bool InsertLifetime,
-                                        Function *ForwardVarArgsTo) {
+                                        Function *ForwardVarArgsTo,
+                                        bool MergeAttributes) {
   assert(CB.getParent() && CB.getFunction() && "Instruction not in function!");
 
   // FIXME: we don't inline callbr yet.
@@ -2509,6 +2510,9 @@
     // Since we are now done with the return instruction, delete it also.
     Returns[0]->eraseFromParent();
 
+    if (MergeAttributes)
+      AttributeFuncs::mergeAttributesForInlining(*Caller, *CalledFunc);
+
     // We are now done with the inlining.
     return InlineResult::success();
   }
@@ -2672,5 +2676,8 @@
     }
   }
 
+  if (MergeAttributes)
+    AttributeFuncs::mergeAttributesForInlining(*Caller, *CalledFunc);
+
   return InlineResult::success();
 }