diff --git a/llvm/include/llvm/Analysis/InlineCost.h b/llvm/include/llvm/Analysis/InlineCost.h
--- a/llvm/include/llvm/Analysis/InlineCost.h
+++ b/llvm/include/llvm/Analysis/InlineCost.h
@@ -246,6 +246,20 @@
     CallBase &Call, Function *Callee, TargetTransformInfo &CalleeTTI,
     function_ref<const TargetLibraryInfo &(Function &)> GetTLI);
 
+/// Get the cost estimate ignoring thresholds. This is similar to getInlineCost
+/// when passed InlineParams::ComputeFullInlineCost, or a non-null ORE. It
+/// uses default InlineParams otherwise.
+/// Contrary to getInlineCost, which makes a threshold-based final evaluation of
+/// should/shouldn't inline, captured in InlineResult, getInliningCostEstimate
+/// returns:
+/// - None, if the inlining cannot happen (is illegal)
+/// - an integer, representing the cost.
+Optional<int> getInliningCostEstimate(
+    CallBase &Call, TargetTransformInfo &CalleeTTI,
+    std::function<AssumptionCache &(Function &)> &GetAssumptionCache,
+    Optional<function_ref<BlockFrequencyInfo &(Function &)>> GetBFI,
+    ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE);
+
 /// Minimal filter to detect invalid constructs for inlining.
 InlineResult isInlineViable(Function &Callee);
 } // namespace llvm
diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -427,6 +427,9 @@
   /// Attempt to evaluate indirect calls to boost its inline cost.
   const bool BoostIndirectCalls;
 
+  /// Ignore the threshold when finalizing analysis.
+  const bool IgnoreThreshold;
+
   /// Inlining cost measured in abstract units, accounts for all the
   /// instructions expected to be executed for a given function invocation.
   /// Instructions that are statically proven to be dead based on call-site
@@ -629,14 +632,14 @@
     else if (NumVectorInstructions <= NumInstructions / 2)
       Threshold -= VectorBonus / 2;
 
-    if (Cost < std::max(1, Threshold))
+    if (IgnoreThreshold || Cost < std::max(1, Threshold))
       return InlineResult::success();
     return InlineResult::failure("Cost over threshold.");
   }
   bool shouldStop() override {
     // Bail out the moment we cross the threshold. This means we'll under-count
     // the cost, but only when undercounting doesn't matter.
-    return Cost >= Threshold && !ComputeFullInlineCost;
+    return !IgnoreThreshold && Cost >= Threshold && !ComputeFullInlineCost;
   }
 
   void onLoadEliminationOpportunity() override {
@@ -694,12 +697,13 @@
       std::function<AssumptionCache &(Function &)> &GetAssumptionCache,
       Optional<function_ref<BlockFrequencyInfo &(Function &)>> &GetBFI,
       ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE, Function &Callee,
-      CallBase &Call, const InlineParams &Params, bool BoostIndirect = true)
+      CallBase &Call, const InlineParams &Params, bool BoostIndirect = true,
+      bool IgnoreThreshold = false)
       : CallAnalyzer(TTI, GetAssumptionCache, GetBFI, PSI, ORE, Callee, Call),
         ComputeFullInlineCost(OptComputeFullInlineCost ||
                               Params.ComputeFullInlineCost || ORE),
         Params(Params), Threshold(Params.DefaultThreshold),
-        BoostIndirectCalls(BoostIndirect) {}
+        BoostIndirectCalls(BoostIndirect), IgnoreThreshold(IgnoreThreshold) {}
 
   /// Annotation Writer for cost annotation
   CostAnnotationWriter Writer;
@@ -2215,6 +2219,30 @@
                        GetAssumptionCache, GetBFI, GetTLI, PSI, ORE);
 }
 
+Optional<int> getInliningCostEstimate(
+    CallBase &Call, TargetTransformInfo &CalleeTTI,
+    std::function<AssumptionCache &(Function &)> &GetAssumptionCache,
+    Optional<function_ref<BlockFrequencyInfo &(Function &)>> GetBFI,
+    ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE) {
+  const InlineParams Params = {/* DefaultThreshold*/ 0,
+                               /*HintThreshold*/ {},
+                               /*ColdThreshold*/ {},
+                               /*OptSizeThreshold*/ {},
+                               /*OptMinSizeThreshold*/ {},
+                               /*HotCallSiteThreshold*/ {},
+                               /*LocallyHotCallSiteThreshold*/ {},
+                               /*ColdCallSiteThreshold*/ {},
+                               /* ComputeFullInlineCost*/ true};
+
+  InlineCostCallAnalyzer CA(CalleeTTI, GetAssumptionCache, GetBFI, PSI, ORE,
+                            *Call.getCalledFunction(), Call, Params, true,
+                            /*IgnoreThreshold*/ true);
+  auto R = CA.analyze();
+  if (!R.isSuccess())
+    return None;
+  return CA.getCost();
+}
+
 Optional<InlineResult> llvm::getAttributeBasedInliningDecision(
     CallBase &Call, Function *Callee, TargetTransformInfo &CalleeTTI,
     function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {