diff --git a/llvm/include/llvm/Analysis/InlineOrder.h b/llvm/include/llvm/Analysis/InlineOrder.h
new file mode 100644
--- /dev/null
+++ b/llvm/include/llvm/Analysis/InlineOrder.h
@@ -0,0 +1,173 @@
+//===- InlineOrder.h - Inlining order abstraction -*- C++ ---*-------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+#ifndef LLVM_ANALYSIS_INLINEORDER_H
+#define LLVM_ANALYSIS_INLINEORDER_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include <algorithm>
+#include <utility>
+
+namespace llvm {
+class CallBase;
+class Function;
+class Module;
+
+template <typename T> class InlineOrder {
+public:
+  using reference = T &;
+  using const_reference = const T &;
+
+  virtual ~InlineOrder() {}
+
+  virtual size_t size() = 0;
+
+  virtual void push(const T &Elt) = 0;
+
+  virtual T pop() = 0;
+
+  virtual const_reference front() = 0;
+
+  virtual void erase_if(function_ref<bool(T)> Pred) = 0;
+
+  bool empty() { return !size(); }
+};
+
+template <typename T, typename Container = SmallVector<T, 16>>
+class DefaultInlineOrder : public InlineOrder<T> {
+  using reference = T &;
+  using const_reference = const T &;
+
+public:
+  size_t size() override { return Calls.size() - FirstIndex; }
+
+  void push(const T &Elt) override { Calls.push_back(Elt); }
+
+  T pop() override {
+    assert(size() > 0);
+    return Calls[FirstIndex++];
+  }
+
+  const_reference front() override {
+    assert(size() > 0);
+    return Calls[FirstIndex];
+  }
+
+  void erase_if(function_ref<bool(T)> Pred) override {
+    Calls.erase(std::remove_if(Calls.begin() + FirstIndex, Calls.end(), Pred),
+                Calls.end());
+  }
+
+private:
+  Container Calls;
+  size_t FirstIndex = 0;
+};
+
+class InlineSizePriority {
+public:
+  InlineSizePriority(int Size) : Size(Size) {}
+
+  static bool isMoreDesirable(const InlineSizePriority &S1,
+                              const InlineSizePriority &S2) {
+    return S1.Size < S2.Size;
+  }
+
+  static InlineSizePriority evaluate(CallBase *CB) {
+    Function *Callee = CB->getCalledFunction();
+    return InlineSizePriority(Callee->getInstructionCount());
+  }
+
+  int Size;
+};
+
+template <typename PriorityT>
+class PriorityInlineOrder : public InlineOrder<std::pair<CallBase *, int>> {
+  using T = std::pair<CallBase *, int>;
+  using HeapT = std::pair<CallBase *, PriorityT>;
+  using reference = T &;
+  using const_reference = const T &;
+
+  static bool cmp(const HeapT &P1, const HeapT &P2) {
+    return PriorityT::isMoreDesirable(P2.second, P1.second);
+  }
+
+  // A call site could become less desirable for inlining because of the size
+  // growth from prior inlining into the callee. This method is used to lazily
+  // update the desirability of a call site if it's decreasing. It is only
+  // called on pop() or front(), not every time the desirability changes. When
+  // the desirability of the front call site decreases, an updated one would be
+  // pushed right back into the heap. For simplicity, those cases where
+  // the desirability of a call site increases are ignored here.
+  void adjust() {
+    bool Changed = false;
+    do {
+      CallBase *CB = Heap.front().first;
+      const PriorityT PreviousGoodness = Heap.front().second;
+      const PriorityT CurrentGoodness = PriorityT::evaluate(CB);
+      Changed = PriorityT::isMoreDesirable(PreviousGoodness, CurrentGoodness);
+      if (Changed) {
+        std::pop_heap(Heap.begin(), Heap.end(), cmp);
+        Heap.pop_back();
+        Heap.push_back({CB, CurrentGoodness});
+        std::push_heap(Heap.begin(), Heap.end(), cmp);
+      }
+    } while (Changed);
+  }
+
+public:
+  size_t size() override { return Heap.size(); }
+
+  void push(const T &Elt) override {
+    CallBase *CB = Elt.first;
+    const int InlineHistoryID = Elt.second;
+    const PriorityT Goodness = PriorityT::evaluate(CB);
+
+    Heap.push_back({CB, Goodness});
+    std::push_heap(Heap.begin(), Heap.end(), cmp);
+    InlineHistoryMap[CB] = InlineHistoryID;
+  }
+
+  T pop() override {
+    assert(size() > 0);
+    adjust();
+
+    CallBase *CB = Heap.front().first;
+    T Result = std::make_pair(CB, InlineHistoryMap[CB]);
+    InlineHistoryMap.erase(CB);
+    std::pop_heap(Heap.begin(), Heap.end(), cmp);
+    Heap.pop_back();
+    return Result;
+  }
+
+  const_reference front() override {
+    assert(size() > 0);
+    adjust();
+
+    CallBase *CB = Heap.front().first;
+    return *InlineHistoryMap.find(CB);
+  }
+
+  void erase_if(function_ref<bool(T)> Pred) override {
+    auto PredWrapper = [=](HeapT P) -> bool {
+      return Pred(std::make_pair(P.first, 0));
+    };
+    Heap.erase(std::remove_if(Heap.begin(), Heap.end(), PredWrapper),
+               Heap.end());
+    std::make_heap(Heap.begin(), Heap.end(), cmp);
+  }
+
+private:
+  SmallVector<HeapT, 16> Heap;
+  DenseMap<CallBase *, int> InlineHistoryMap;
+};
+} // namespace llvm
+#endif // LLVM_ANALYSIS_INLINEORDER_H
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
@@ -31,6 +31,7 @@
 #include "llvm/Analysis/GlobalsModRef.h"
 #include "llvm/Analysis/InlineAdvisor.h"
 #include "llvm/Analysis/InlineCost.h"
+#include "llvm/Analysis/InlineOrder.h"
 #include "llvm/Analysis/LazyCallGraph.h"
 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
 #include "llvm/Analysis/ProfileSummaryInfo.h"
@@ -674,153 +675,6 @@
   return *IAA->getAdvisor();
 }
 
-template <typename T> class InlineOrder {
-public:
-  using reference = T &;
-  using const_reference = const T &;
-
-  virtual ~InlineOrder() {}
-
-  virtual size_t size() = 0;
-
-  virtual void push(const T &Elt) = 0;
-
-  virtual T pop() = 0;
-
-  virtual const_reference front() = 0;
-
-  virtual void erase_if(function_ref<bool(T)> Pred) = 0;
-
-  bool empty() { return !size(); }
-};
-
-template <typename T, typename Container = SmallVector<T, 16>>
-class DefaultInlineOrder : public InlineOrder<T> {
-  using reference = T &;
-  using const_reference = const T &;
-
-public:
-  size_t size() override { return Calls.size() - FirstIndex; }
-
-  void push(const T &Elt) override { Calls.push_back(Elt); }
-
-  T pop() override {
-    assert(size() > 0);
-    return Calls[FirstIndex++];
-  }
-
-  const_reference front() override {
-    assert(size() > 0);
-    return Calls[FirstIndex];
-  }
-
-  void erase_if(function_ref<bool(T)> Pred) override {
-    Calls.erase(std::remove_if(Calls.begin() + FirstIndex, Calls.end(), Pred),
-                Calls.end());
-  }
-
-private:
-  Container Calls;
-  size_t FirstIndex = 0;
-};
-
-class Priority {
-public:
-  Priority(int Size) : Size(Size) {}
-
-  static bool isMoreDesirable(const Priority &S1, const Priority &S2) {
-    return S1.Size < S2.Size;
-  }
-
-  static Priority evaluate(CallBase *CB) {
-    Function *Callee = CB->getCalledFunction();
-    return Priority(Callee->getInstructionCount());
-  }
-
-  int Size;
-};
-
-template <typename PriorityT>
-class PriorityInlineOrder : public InlineOrder<std::pair<CallBase *, int>> {
-  using T = std::pair<CallBase *, int>;
-  using HeapT = std::pair<CallBase *, PriorityT>;
-  using reference = T &;
-  using const_reference = const T &;
-
-  static bool cmp(const HeapT &P1, const HeapT &P2) {
-    return PriorityT::isMoreDesirable(P2.second, P1.second);
-  }
-
-  // A call site could become less desirable for inlining because of the size
-  // growth from prior inlining into the callee. This method is used to lazily
-  // update the desirability of a call site if it's decreasing. It is only
-  // called on pop() or front(), not every time the desirability changes. When
-  // the desirability of the front call site decreases, an updated one would be
-  // pushed right back into the heap. For simplicity, those cases where
-  // the desirability of a call site increases are ignored here.
-  void adjust() {
-    bool Changed = false;
-    do {
-      CallBase *CB = Heap.front().first;
-      const PriorityT PreviousGoodness = Heap.front().second;
-      const PriorityT CurrentGoodness = PriorityT::evaluate(CB);
-      Changed = PriorityT::isMoreDesirable(PreviousGoodness, CurrentGoodness);
-      if (Changed) {
-        std::pop_heap(Heap.begin(), Heap.end(), cmp);
-        Heap.pop_back();
-        Heap.push_back({CB, CurrentGoodness});
-        std::push_heap(Heap.begin(), Heap.end(), cmp);
-      }
-    } while (Changed);
-  }
-
-public:
-  size_t size() override { return Heap.size(); }
-
-  void push(const T &Elt) override {
-    CallBase *CB = Elt.first;
-    const int InlineHistoryID = Elt.second;
-    const PriorityT Goodness = PriorityT::evaluate(CB);
-
-    Heap.push_back({CB, Goodness});
-    std::push_heap(Heap.begin(), Heap.end(), cmp);
-    InlineHistoryMap[CB] = InlineHistoryID;
-  }
-
-  T pop() override {
-    assert(size() > 0);
-    adjust();
-
-    CallBase *CB = Heap.front().first;
-    T Result = std::make_pair(CB, InlineHistoryMap[CB]);
-    InlineHistoryMap.erase(CB);
-    std::pop_heap(Heap.begin(), Heap.end(), cmp);
-    Heap.pop_back();
-    return Result;
-  }
-
-  const_reference front() override {
-    assert(size() > 0);
-    adjust();
-
-    CallBase *CB = Heap.front().first;
-    return *InlineHistoryMap.find(CB);
-  }
-
-  void erase_if(function_ref<bool(T)> Pred) override {
-    auto PredWrapper = [=](HeapT P) -> bool {
-      return Pred(std::make_pair(P.first, 0));
-    };
-    Heap.erase(std::remove_if(Heap.begin(), Heap.end(), PredWrapper),
-               Heap.end());
-    std::make_heap(Heap.begin(), Heap.end(), cmp);
-  }
-
-private:
-  SmallVector<HeapT, 16> Heap;
-  DenseMap<CallBase *, int> InlineHistoryMap;
-};
-
 PreservedAnalyses InlinerPass::run(LazyCallGraph::SCC &InitialC,
                                    CGSCCAnalysisManager &AM, LazyCallGraph &CG,
                                    CGSCCUpdateResult &UR) {
@@ -868,7 +722,7 @@
   // incrementally maknig a single function grow in a super linear fashion.
   std::unique_ptr<InlineOrder<std::pair<CallBase *, int>>> Calls;
   if (InlineEnablePriorityOrder)
-    Calls = std::make_unique<PriorityInlineOrder<Priority>>();
+    Calls = std::make_unique<PriorityInlineOrder<InlineSizePriority>>();
   else
     Calls = std::make_unique<DefaultInlineOrder<std::pair<CallBase *, int>>>();
   assert(Calls != nullptr && "Expected an initialized InlineOrder");