Index: lib/Transforms/IPO/LowerTypeTests.cpp
===================================================================
--- lib/Transforms/IPO/LowerTypeTests.cpp
+++ lib/Transforms/IPO/LowerTypeTests.cpp
@@ -1702,11 +1702,28 @@
     return false;
 
   // If only some of the modules were split, we cannot correctly handle
-  // code that contains type tests.
-  if (TypeTestFunc && !TypeTestFunc->use_empty() &&
-      ((ExportSummary && ExportSummary->partiallySplitLTOUnits()) ||
-       (ImportSummary && ImportSummary->partiallySplitLTOUnits())))
-    report_fatal_error("inconsistent LTO Unit splitting with llvm.type.test");
+  // code that contains type tests. Check this during the serial whole program
+  // analysis export phase.
+  if (ExportSummary && ExportSummary->partiallySplitLTOUnits()) {
+    // First check if there are type tests in the merged LTO module IR.
+    if (TypeTestFunc && !TypeTestFunc->use_empty())
+      report_fatal_error("inconsistent LTO Unit splitting with llvm.type.test");
+
+    // Otherwise check if there are any recorded in the summary from the
+    // ThinLTO module.
+    for (auto &P : *ExportSummary) {
+      for (auto &S : P.second.SummaryList) {
+        auto *FS = dyn_cast<FunctionSummary>(S.get());
+        if (!FS)
+          continue;
+        if (!FS->type_test_assume_vcalls().empty() ||
+            !FS->type_test_assume_const_vcalls().empty() ||
+            !FS->type_tests().empty())
+          report_fatal_error(
+              "inconsistent LTO Unit splitting with llvm.type.test");
+      }
+    }
+  }
 
   if (ImportSummary) {
     if (TypeTestFunc) {
Index: lib/Transforms/IPO/WholeProgramDevirt.cpp
===================================================================
--- lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -1563,13 +1563,32 @@
   Function *AssumeFunc = M.getFunction(Intrinsic::getName(Intrinsic::assume));
 
   // If only some of the modules were split, we cannot correctly handle
-  // code that contains type tests or type checked loads.
-  if ((ExportSummary && ExportSummary->partiallySplitLTOUnits()) ||
-      (ImportSummary && ImportSummary->partiallySplitLTOUnits())) {
+  // code that contains type tests or type checked loads. Check this during
+  // the serial whole program analysis export phase.
+  if (ExportSummary && ExportSummary->partiallySplitLTOUnits()) {
+    // First check if there are type tests / type checked loads in the
+    // merged LTO module IR.
     if ((TypeTestFunc && !TypeTestFunc->use_empty()) ||
         (TypeCheckedLoadFunc && !TypeCheckedLoadFunc->use_empty()))
       report_fatal_error("inconsistent LTO Unit splitting with llvm.type.test "
                          "or llvm.type.checked.load");
+    // Otherwise check if there are any recorded in the summary from the
+    // ThinLTO module.
+    for (auto &P : *ExportSummary) {
+      for (auto &S : P.second.SummaryList) {
+        auto *FS = dyn_cast<FunctionSummary>(S.get());
+        if (!FS)
+          continue;
+        if (!FS->type_test_assume_vcalls().empty() ||
+            !FS->type_checked_load_vcalls().empty() ||
+            !FS->type_test_assume_const_vcalls().empty() ||
+            !FS->type_checked_load_const_vcalls().empty() ||
+            !FS->type_tests().empty())
+          report_fatal_error(
+              "inconsistent LTO Unit splitting with llvm.type.test "
+              "or llvm.type.checked.load");
+      }
+    }
     return false;
   }
 
Index: test/ThinLTO/X86/cfi-devirt.ll
===================================================================
--- test/ThinLTO/X86/cfi-devirt.ll
+++ test/ThinLTO/X86/cfi-devirt.ll
@@ -20,8 +20,8 @@
 ; RUN:   -r=%t.o,_ZN1B1fEi, \
 ; RUN:   -r=%t.o,_ZN1C1fEi, \
 ; RUN:   -r=%t.o,_ZTV1B,px \
-; RUN:   -r=%t.o,_ZTV1C,px 2>&1 | FileCheck %s --check-prefix=REMARK -dump-input=always
-; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR -dump-input=always
+; RUN:   -r=%t.o,_ZTV1C,px 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ; New PM
 ; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39436.
@@ -39,17 +39,18 @@
 ; RUN:   -r=%t.o,_ZN1B1fEi, \
 ; RUN:   -r=%t.o,_ZN1C1fEi, \
 ; RUN:   -r=%t.o,_ZTV1B,px \
-; RUN:   -r=%t.o,_ZTV1C,px 2>&1 | FileCheck %s --check-prefix=REMARK -dump-input=always
-; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR -dump-input=always
+; RUN:   -r=%t.o,_ZTV1C,px 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ; REMARK: single-impl: devirtualized a call to _ZN1A1nEi
 
 ; Next check that we emit an error when trying to LTO link this module
 ; containing an llvm.type.checked.load (with a split LTO Unit) with one
-; that does not have a split LTO Unit.
+; that does not have a split LTO Unit. Use -thinlto-distributed-indexes
+; to ensure it is being caught in the thin link.
 ; RUN: opt -thinlto-bc -o %t2.o %S/Inputs/empty.ll
-; RUN: not llvm-lto2 run %t.o %t2.o -save-temps -pass-remarks=. \
-; RUN:   -verify-machineinstrs=0 -thinlto-threads=1 \
+; RUN: not llvm-lto2 run %t.o %t2.o -thinlto-distributed-indexes \
+; RUN:   -verify-machineinstrs=0 \
 ; RUN:   -o %t3 \
 ; RUN:   -r=%t.o,test,px \
 ; RUN:   -r=%t.o,_ZN1A1nEi,p \
@@ -62,7 +63,7 @@
 ; RUN:   -r=%t.o,_ZN1B1fEi, \
 ; RUN:   -r=%t.o,_ZN1C1fEi, \
 ; RUN:   -r=%t.o,_ZTV1B,px \
-; RUN:   -r=%t.o,_ZTV1C,px 2>&1 | FileCheck %s --check-prefix=ERROR -dump-input=always
+; RUN:   -r=%t.o,_ZTV1C,px 2>&1 | FileCheck %s --check-prefix=ERROR
 ; ERROR: LLVM ERROR: inconsistent LTO Unit splitting with llvm.type.test or llvm.type.checked.load
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"