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
@@ -670,54 +670,6 @@
   return *IAA->getAdvisor();
 }
 
-template <typename T> class InlineOrder {
-public:
-  using reference = T &;
-
-  virtual ~InlineOrder() {}
-
-  virtual size_t size() = 0;
-
-  virtual void push(const T &Elt) = 0;
-
-  virtual void pop() = 0;
-
-  virtual 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 &;
-
-public:
-  size_t size() override { return Calls.end() - Calls.begin() - FirstIndex; }
-
-  void push(const T &Elt) override { Calls.push_back(Elt); }
-
-  void pop() override {
-    assert(size() > 0);
-    FirstIndex++;
-  }
-
-  reference front() override {
-    assert(Calls.begin() + FirstIndex < Calls.end());
-    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;
-};
-
 PreservedAnalyses InlinerPass::run(LazyCallGraph::SCC &InitialC,
                                    CGSCCAnalysisManager &AM, LazyCallGraph &CG,
                                    CGSCCUpdateResult &UR) {
@@ -762,7 +714,7 @@
   // this model, but it is uniformly spread across all the functions in the SCC
   // and eventually they all become too large to inline, rather than
   // incrementally maknig a single function grow in a super linear fashion.
-  DefaultInlineOrder<std::pair<CallBase *, int>> Calls;
+  SmallVector<std::pair<CallBase *, int>, 16> Calls;
 
   // Populate the initial list of calls in this SCC.
   for (auto &N : InitialC) {
@@ -777,7 +729,7 @@
       if (auto *CB = dyn_cast<CallBase>(&I))
         if (Function *Callee = CB->getCalledFunction()) {
           if (!Callee->isDeclaration())
-            Calls.push({CB, -1});
+            Calls.push_back({CB, -1});
           else if (!isa<IntrinsicInst>(I)) {
             using namespace ore;
             setInlineRemark(*CB, "unavailable definition");
@@ -814,12 +766,12 @@
 
   // Loop forward over all of the calls. Note that we cannot cache the size as
   // inlining can introduce new calls that need to be processed.
-  while (!Calls.empty()) {
+  for (int I = 0; I < (int)Calls.size(); ++I) {
     // We expect the calls to typically be batched with sequences of calls that
     // have the same caller, so we first set up some shared infrastructure for
     // this caller. We also do any pruning we can at this layer on the caller
     // alone.
-    Function &F = *(Calls.front()).first->getCaller();
+    Function &F = *Calls[I].first->getCaller();
     LazyCallGraph::Node &N = *CG.lookup(F);
     if (CG.lookupSCC(N) != C)
       continue;
@@ -836,9 +788,8 @@
     // We bail out as soon as the caller has to change so we can update the
     // call graph and prepare the context of that new caller.
     bool DidInline = false;
-    while (!Calls.empty() && Calls.front().first->getCaller() == &F) {
-      auto &P = Calls.front();
-      Calls.pop();
+    for (; I < (int)Calls.size() && Calls[I].first->getCaller() == &F; ++I) {
+      auto &P = Calls[I];
       CallBase *CB = P.first;
       const int InlineHistoryID = P.second;
       Function &Callee = *CB->getCalledFunction();
@@ -908,7 +859,7 @@
           }
           if (NewCallee)
             if (!NewCallee->isDeclaration())
-              Calls.push({ICB, NewHistoryID});
+              Calls.push_back({ICB, NewHistoryID});
         }
       }
 
@@ -925,9 +876,12 @@
         // made dead by this operation on other functions).
         Callee.removeDeadConstantUsers();
         if (Callee.use_empty() && !CG.isLibFunction(Callee)) {
-          Calls.erase_if([&](const std::pair<CallBase *, int> &Call) {
-            return Call.first->getCaller() == &Callee;
-          });
+          Calls.erase(
+              std::remove_if(Calls.begin() + I + 1, Calls.end(),
+                             [&](const std::pair<CallBase *, int> &Call) {
+                               return Call.first->getCaller() == &Callee;
+                             }),
+              Calls.end());
           // Clear the body and queue the function itself for deletion when we
           // finish inlining and call graph updates.
           // Note that after this point, it is an error to do anything other
@@ -945,6 +899,10 @@
         Advice->recordInlining();
     }
 
+    // Back the call index up by one to put us in a good position to go around
+    // the outer loop.
+    --I;
+
     if (!DidInline)
       continue;
     Changed = true;