Index: llvm/include/llvm/IR/ModuleSummaryIndex.h
===================================================================
--- llvm/include/llvm/IR/ModuleSummaryIndex.h
+++ llvm/include/llvm/IR/ModuleSummaryIndex.h
@@ -340,6 +340,10 @@
   ArrayRef<ConstVCall> type_checked_load_const_vcalls() const {
     return TypeCheckedLoadConstVCalls;
   }
+
+  /// Add a type test to the summary. This is used by WholeProgramDevirt if we
+  /// were unable to devirtualize a checked call.
+  void addTypeTest(GlobalValue::GUID Guid) { TypeTests.push_back(Guid); }
 };
 
 template <> struct DenseMapInfo<FunctionSummary::VFuncId> {
Index: llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
===================================================================
--- llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -287,6 +287,7 @@
 
 struct CallSiteInfo {
   std::vector<VirtualCallSite> CallSites;
+  std::vector<FunctionSummary *> TypeCheckedLoadUsers;
 };
 
 struct VTableSlotInfo {
@@ -1022,7 +1023,8 @@
       M.getFunction(Intrinsic::getName(Intrinsic::type_checked_load));
   Function *AssumeFunc = M.getFunction(Intrinsic::getName(Intrinsic::assume));
 
-  if ((!TypeTestFunc || TypeTestFunc->use_empty() || !AssumeFunc ||
+  if (Action != PassSummaryAction::Export &&
+      (!TypeTestFunc || TypeTestFunc->use_empty() || !AssumeFunc ||
        AssumeFunc->use_empty()) &&
       (!TypeCheckedLoadFunc || TypeCheckedLoadFunc->use_empty()))
     return false;
@@ -1040,6 +1042,33 @@
   if (TypeIdMap.empty())
     return true;
 
+  if (Action == PassSummaryAction::Export) {
+    DenseMap<GlobalValue::GUID, TinyPtrVector<Metadata *>> MetadataByGUID;
+    for (auto &P : TypeIdMap) {
+      if (auto *TypeId = dyn_cast<MDString>(P.first))
+        MetadataByGUID[GlobalValue::getGUID(TypeId->getString())].push_back(
+            TypeId);
+    }
+
+    for (auto &P : *Summary) {
+      for (auto &S : P.second) {
+        auto *FS = dyn_cast<FunctionSummary>(S.get());
+        if (!FS)
+          continue;
+        // FIXME: Only add live functions.
+        for (FunctionSummary::VFuncId VF : FS->type_checked_load_vcalls())
+          for (Metadata *MD : MetadataByGUID[VF.GUID])
+            CallSlots[{MD, VF.Offset}].CSInfo.TypeCheckedLoadUsers.push_back(
+                FS);
+        for (const FunctionSummary::ConstVCall &VC :
+             FS->type_checked_load_const_vcalls())
+          for (Metadata *MD : MetadataByGUID[VC.VFunc.GUID])
+            CallSlots[{MD, VC.VFunc.Offset}]
+                .ConstCSInfo[VC.Args].TypeCheckedLoadUsers.push_back(FS);
+      }
+    }
+  }
+
   // For each (type, offset) pair:
   bool DidVirtualConstProp = false;
   std::map<std::string, Function*> DevirtTargets;
@@ -1048,19 +1077,31 @@
     // function implementation at offset S.first.ByteOffset, and add to
     // TargetsForSlot.
     std::vector<VirtualCallTarget> TargetsForSlot;
-    if (!tryFindVirtualCallTargets(TargetsForSlot, TypeIdMap[S.first.TypeID],
-                                   S.first.ByteOffset))
-      continue;
-
-    if (!trySingleImplDevirt(TargetsForSlot, S.second) &&
-        tryVirtualConstProp(TargetsForSlot, S.second))
+    if (tryFindVirtualCallTargets(TargetsForSlot, TypeIdMap[S.first.TypeID],
+                                  S.first.ByteOffset)) {
+      if (!trySingleImplDevirt(TargetsForSlot, S.second) &&
+          tryVirtualConstProp(TargetsForSlot, S.second))
         DidVirtualConstProp = true;
 
-    // Collect functions devirtualized at least for one call site for stats.
-    if (RemarksEnabled)
-      for (const auto &T : TargetsForSlot)
-        if (T.WasDevirt)
-          DevirtTargets[T.Fn->getName()] = T.Fn;
+      // Collect functions devirtualized at least for one call site for stats.
+      if (RemarksEnabled)
+        for (const auto &T : TargetsForSlot)
+          if (T.WasDevirt)
+            DevirtTargets[T.Fn->getName()] = T.Fn;
+    }
+
+    // If we are exporting and any llvm.type.checked.load intrinsics were *not*
+    // devirtualized, we need to add the resulting llvm.type.test intrinsics to
+    // the function summaries so that the LowerTypeTests pass will export them.
+    if (Action == PassSummaryAction::Export && isa<MDString>(S.first.TypeID)) {
+      auto GUID =
+          GlobalValue::getGUID(cast<MDString>(S.first.TypeID)->getString());
+      for (auto FS : S.second.CSInfo.TypeCheckedLoadUsers)
+        FS->addTypeTest(GUID);
+      for (auto &CCS : S.second.ConstCSInfo)
+        for (auto FS : CCS.second.TypeCheckedLoadUsers)
+          FS->addTypeTest(GUID);
+    }
   }
 
   if (RemarksEnabled) {
Index: llvm/test/Transforms/WholeProgramDevirt/Inputs/export.yaml
===================================================================
--- /dev/null
+++ llvm/test/Transforms/WholeProgramDevirt/Inputs/export.yaml
@@ -0,0 +1,20 @@
+---
+GlobalValueMap:
+  42:
+    - TypeTestAssumeVCalls:
+        - GUID: 14276520915468743435  # typeid1
+          Offset: 0
+      TypeCheckedLoadVCalls:
+        - GUID: 15427464259790519041  # typeid2
+          Offset: 0
+      TypeTestAssumeConstVCalls:
+        - VFunc:
+            GUID: 3515965990081467659  # typeid3
+            Offset: 0
+          Args: [12, 24]
+      TypeCheckedLoadConstVCalls:
+        - VFunc:
+            GUID: 17525413373118030901  # typeid4
+            Offset: 0
+          Args: [24, 12]
+...
Index: llvm/test/Transforms/WholeProgramDevirt/export-unsuccessful-checked.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/WholeProgramDevirt/export-unsuccessful-checked.ll
@@ -0,0 +1,30 @@
+; RUN: opt -wholeprogramdevirt -wholeprogramdevirt-summary-action=export -wholeprogramdevirt-read-summary=%S/Inputs/export.yaml -wholeprogramdevirt-write-summary=%t -o /dev/null %s
+; RUN: FileCheck %s < %t
+
+; CHECK:     - TypeTests:
+; CHECK-NEXT:   - 15427464259790519041
+; CHECK-NEXT:   - 17525413373118030901
+; CHECK-NEXT:  TypeTestAssumeVCalls:
+
+@vt1a = constant void (i8*)* @vf1a, !type !0
+@vt1b = constant void (i8*)* @vf1b, !type !0
+@vt2a = constant void (i8*)* @vf2a, !type !1
+@vt2b = constant void (i8*)* @vf2b, !type !1
+@vt3a = constant void (i8*)* @vf3a, !type !2
+@vt3b = constant void (i8*)* @vf3b, !type !2
+@vt4a = constant void (i8*)* @vf4a, !type !3
+@vt4b = constant void (i8*)* @vf4b, !type !3
+
+declare void @vf1a(i8*)
+declare void @vf1b(i8*)
+declare void @vf2a(i8*)
+declare void @vf2b(i8*)
+declare void @vf3a(i8*)
+declare void @vf3b(i8*)
+declare void @vf4a(i8*)
+declare void @vf4b(i8*)
+
+!0 = !{i32 0, !"typeid1"}
+!1 = !{i32 0, !"typeid2"}
+!2 = !{i32 0, !"typeid3"}
+!3 = !{i32 0, !"typeid4"}