Index: unittests/Passes/CMakeLists.txt
===================================================================
--- unittests/Passes/CMakeLists.txt
+++ unittests/Passes/CMakeLists.txt
@@ -1,3 +1,6 @@
+# Needed by LLVM's CMake checks because this file defines multiple targets.
+set(LLVM_OPTIONAL_SOURCES TestPlugin.cpp)
+
 set(LLVM_LINK_COMPONENTS Support Passes Core)
 
 # If plugins are disabled, this test will disable itself at runtime. Otherwise,
@@ -9,7 +12,7 @@
 add_llvm_unittest(PluginsTests PluginsTest.cpp)
 export_executable_symbols(PluginsTests)
 
-add_library(TestPlugin MODULE TestPlugin.cxx)
+add_library(TestPlugin MODULE TestPlugin.cpp)
 
 set_output_directory(TestPlugin
   BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}
Index: unittests/Passes/TestPlugin.cpp
===================================================================
--- unittests/Passes/TestPlugin.cpp
+++ unittests/Passes/TestPlugin.cpp
@@ -1,4 +1,4 @@
-//===- unittests/Passes/Plugins/Plugin.cxx --------------------------------===//
+//===- unittests/Passes/Plugins/Plugin.cpp --------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
Index: unittests/Passes/TestPlugin.cxx
===================================================================
--- unittests/Passes/TestPlugin.cxx
+++ unittests/Passes/TestPlugin.cxx
@@ -1,39 +0,0 @@
-//===- unittests/Passes/Plugins/Plugin.cxx --------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Passes/PassBuilder.h"
-#include "llvm/Passes/PassPlugin.h"
-
-#include "TestPlugin.h"
-
-using namespace llvm;
-
-struct TestModulePass : public PassInfoMixin<TestModulePass> {
-  PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM) {
-    return PreservedAnalyses::all();
-  }
-};
-
-void registerCallbacks(PassBuilder &PB) {
-  PB.registerPipelineParsingCallback(
-      [](StringRef Name, ModulePassManager &PM,
-         ArrayRef<PassBuilder::PipelineElement> InnerPipeline) {
-        if (Name == "plugin-pass") {
-          PM.addPass(TestModulePass());
-          return true;
-        }
-        return false;
-      });
-}
-
-extern "C" ::llvm::PassPluginLibraryInfo LLVM_ATTRIBUTE_WEAK LLVM_PLUGIN_EXPORT
-llvmGetPassPluginInfo() {
-  return {LLVM_PLUGIN_API_VERSION, TEST_PLUGIN_NAME, TEST_PLUGIN_VERSION,
-          registerCallbacks};
-}
Index: unittests/Support/DynamicLibrary/CMakeLists.txt
===================================================================
--- unittests/Support/DynamicLibrary/CMakeLists.txt
+++ unittests/Support/DynamicLibrary/CMakeLists.txt
@@ -1,6 +1,9 @@
+# Needed by LLVM's CMake checks because this file defines multiple targets.
+set(LLVM_OPTIONAL_SOURCES ExportedFuncs.cpp PipSqueak.cpp)
+
 set(LLVM_LINK_COMPONENTS Support)
 
-add_library(DynamicLibraryLib STATIC ExportedFuncs.cxx)
+add_library(DynamicLibraryLib STATIC ExportedFuncs.cpp)
 set_target_properties(DynamicLibraryLib PROPERTIES FOLDER "Tests")
 
 add_llvm_unittest(DynamicLibraryTests DynamicLibraryTest.cpp)
@@ -8,7 +11,7 @@
 export_executable_symbols(DynamicLibraryTests)
 
 function(dynlib_add_module NAME)
-  add_library(${NAME} SHARED PipSqueak.cxx)
+  add_library(${NAME} SHARED PipSqueak.cpp)
   set_target_properties(${NAME} PROPERTIES FOLDER "Tests")
 
   set_output_directory(${NAME}
Index: unittests/Support/DynamicLibrary/ExportedFuncs.cpp
===================================================================
--- unittests/Support/DynamicLibrary/ExportedFuncs.cpp
+++ unittests/Support/DynamicLibrary/ExportedFuncs.cpp
@@ -1,4 +1,4 @@
-//===- llvm/unittest/Support/DynamicLibrary/DynamicLibraryLib.cpp ---------===//
+//===- llvm/unittest/Support/DynamicLibrary/ExportedFuncs.cpp -------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
Index: unittests/Support/DynamicLibrary/ExportedFuncs.cxx
===================================================================
--- unittests/Support/DynamicLibrary/ExportedFuncs.cxx
+++ unittests/Support/DynamicLibrary/ExportedFuncs.cxx
@@ -1,16 +0,0 @@
-//===- llvm/unittest/Support/DynamicLibrary/DynamicLibraryLib.cpp ---------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "PipSqueak.h"
-
-#ifndef PIPSQUEAK_TESTA_RETURN
-#define PIPSQUEAK_TESTA_RETURN "ProcessCall"
-#endif
-
-extern "C" PIPSQUEAK_EXPORT const char *TestA() { return PIPSQUEAK_TESTA_RETURN; }
Index: unittests/Support/DynamicLibrary/PipSqueak.cpp
===================================================================
--- unittests/Support/DynamicLibrary/PipSqueak.cpp
+++ unittests/Support/DynamicLibrary/PipSqueak.cpp
@@ -1,4 +1,4 @@
-//===- llvm/unittest/Support/DynamicLibrary/PipSqueak.cxx -----------------===//
+//===- llvm/unittest/Support/DynamicLibrary/PipSqueak.cpp -----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -46,4 +46,4 @@
 }
 
 #define PIPSQUEAK_TESTA_RETURN "LibCall"
-#include "ExportedFuncs.cxx"
+#include "ExportedFuncs.cpp"
Index: unittests/Support/DynamicLibrary/PipSqueak.cxx
===================================================================
--- unittests/Support/DynamicLibrary/PipSqueak.cxx
+++ unittests/Support/DynamicLibrary/PipSqueak.cxx
@@ -1,49 +0,0 @@
-//===- llvm/unittest/Support/DynamicLibrary/PipSqueak.cxx -----------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "PipSqueak.h"
-
-struct Global {
-  std::string *Str;
-  std::vector<std::string> *Vec;
-  Global() : Str(nullptr), Vec(nullptr) {}
-  ~Global() {
-    if (Str) {
-      if (Vec)
-        Vec->push_back(*Str);
-      *Str = "Global::~Global";
-    }
-  }
-};
-
-static Global Glb;
-
-struct Local {
-  std::string &Str;
-  Local(std::string &S) : Str(S) {
-    Str = "Local::Local";
-    if (Glb.Str && !Glb.Str->empty())
-      Str += std::string("(") + *Glb.Str + std::string(")");
-  }
-  ~Local() { Str = "Local::~Local"; }
-};
-
-
-extern "C" PIPSQUEAK_EXPORT void SetStrings(std::string &GStr,
-                                            std::string &LStr) {
-  Glb.Str = &GStr;
-  static Local Lcl(LStr);
-}
-
-extern "C" PIPSQUEAK_EXPORT void TestOrder(std::vector<std::string> &V) {
-  Glb.Vec = &V;
-}
-
-#define PIPSQUEAK_TESTA_RETURN "LibCall"
-#include "ExportedFuncs.cxx"