diff --git a/infer/src/cost/cost.ml b/infer/src/cost/cost.ml
index a24ccbc82..517a27a96 100644
--- a/infer/src/cost/cost.ml
+++ b/infer/src/cost/cost.ml
@@ -84,10 +84,18 @@ module InstrBasicCostWithReason = struct
                   CostDomain.of_operation_cost (model model_env ~ret inferbo_mem)
               | None -> (
                 match Tenv.get_summary_formals tenv ~get_summary ~get_formals callee_pname with
-                | `Found ({CostDomain.post= callee_cost_record}, callee_formals) ->
-                    CostDomain.map callee_cost_record ~f:(fun callee_cost ->
-                        instantiate_cost integer_type_widths ~inferbo_caller_mem:inferbo_mem
-                          ~callee_pname ~callee_formals ~params ~callee_cost ~loc )
+                | `Found ({CostDomain.post= callee_cost_record}, callee_formals) -> (
+                    let instantiated_cost =
+                      CostDomain.map callee_cost_record ~f:(fun callee_cost ->
+                          instantiate_cost integer_type_widths ~inferbo_caller_mem:inferbo_mem
+                            ~callee_pname ~callee_formals ~params ~callee_cost ~loc )
+                    in
+                    match CostDomain.get_operation_cost callee_cost_record with
+                    | {cost; top_pname_opt= None} when BasicCost.is_top cost ->
+                        CostDomain.add_top_pname_opt CostKind.OperationCost instantiated_cost
+                          (Some callee_pname)
+                    | _ ->
+                        instantiated_cost )
                 | `FoundFromSubclass
                     (callee_pname, {CostDomain.post= callee_cost_record}, callee_formals) ->
                     (* Note: It ignores top cost of subclass to avoid its propagations. *)
@@ -178,8 +186,16 @@ module WorstCaseCost = struct
 
   let compute tenv extras cfg =
     let init = CostDomain.zero_record in
-    InstrCFG.fold_nodes cfg ~init ~f:(fun acc pair ->
-        exec_node tenv extras pair |> CostDomain.plus acc )
+    let cost =
+      InstrCFG.fold_nodes cfg ~init ~f:(fun acc pair ->
+          exec_node tenv extras pair |> CostDomain.plus acc )
+    in
+    Option.iter (CostDomain.get_operation_cost cost).top_pname_opt ~f:(fun top_pname ->
+        ScubaLogging.log_message ~label:"unmodeled_function_top_cost"
+          ~message:(F.asprintf "Unmodeled Function[Top Cost] : %a" Procname.pp top_pname) ;
+        Logging.(debug Analysis Verbose)
+          "@ Unmodeled Function[Top Cost]: %a@\n" Procname.pp top_pname ) ;
+    cost
 end
 
 let is_report_suppressed pname =
diff --git a/infer/src/cost/costDomain.ml b/infer/src/cost/costDomain.ml
index 6c8e9efdc..02fcee964 100644
--- a/infer/src/cost/costDomain.ml
+++ b/infer/src/cost/costDomain.ml
@@ -31,6 +31,8 @@ module BasicCostWithReason = struct
     {record with cost= BasicCost.subst callee_pname location record.cost eval_sym}
 
 
+  (* When we fold the nodes while traversing the cfg,
+     make sure we only keep the first top cost callee we see *)
   let plus record1 record2 =
     { cost= BasicCost.plus record1.cost record2.cost
     ; top_pname_opt= Option.first_some record1.top_pname_opt record2.top_pname_opt }
@@ -78,6 +80,12 @@ let pp_summary fmt {post} = F.fprintf fmt "@\n Post: %a @\n" VariantCostMap.pp p
 
 let get_cost_kind kind cost_record = VariantCostMap.get kind cost_record
 
+let add_top_pname_opt kind cost_record top_pname_opt =
+  VariantCostMap.update kind
+    (function Some cost_with_reason -> Some {cost_with_reason with top_pname_opt} | _ -> None)
+    cost_record
+
+
 let get_operation_cost cost_record = get_cost_kind CostKind.OperationCost cost_record
 
 let map ~f cost_record = VariantCostMap.map f cost_record
diff --git a/infer/src/cost/costDomain.mli b/infer/src/cost/costDomain.mli
index f0b7658b8..6b0095b8d 100644
--- a/infer/src/cost/costDomain.mli
+++ b/infer/src/cost/costDomain.mli
@@ -58,6 +58,8 @@ val pp_summary : F.formatter -> summary -> unit
 
 val get_cost_kind : CostKind.t -> t -> BasicCostWithReason.t
 
+val add_top_pname_opt : CostKind.t -> t -> Procname.t option -> t
+
 val get_operation_cost : t -> BasicCostWithReason.t
 
 val map : f:(BasicCostWithReason.t -> BasicCostWithReason.t) -> t -> t