diff --git a/clang/include/clang/Driver/Action.h b/clang/include/clang/Driver/Action.h
--- a/clang/include/clang/Driver/Action.h
+++ b/clang/include/clang/Driver/Action.h
@@ -436,26 +436,6 @@
   }
 };
 
-class HeaderModulePrecompileJobAction : public PrecompileJobAction {
-  void anchor() override;
-
-  const char *ModuleName;
-
-public:
-  HeaderModulePrecompileJobAction(Action *Input, types::ID OutputType,
-                                  const char *ModuleName);
-
-  static bool classof(const Action *A) {
-    return A->getKind() == HeaderModulePrecompileJobClass;
-  }
-
-  void addModuleHeaderInput(Action *Input) {
-    getInputs().push_back(Input);
-  }
-
-  const char *getModuleName() const { return ModuleName; }
-};
-
 class ExtractAPIJobAction : public JobAction {
   void anchor() override;
 
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5934,8 +5934,6 @@
   HelpText<"Generate pre-compiled module file from a module map">;
 def emit_module_interface : Flag<["-"], "emit-module-interface">,
   HelpText<"Generate pre-compiled module file from a C++ module interface">;
-def emit_header_module : Flag<["-"], "emit-header-module">,
-  HelpText<"Generate pre-compiled module file from a set of header files">;
 def emit_header_unit : Flag<["-"], "emit-header-unit">,
   HelpText<"Generate C++20 header units from header files">;
 def emit_pch : Flag<["-"], "emit-pch">,
diff --git a/clang/include/clang/Frontend/FrontendActions.h b/clang/include/clang/Frontend/FrontendActions.h
--- a/clang/include/clang/Frontend/FrontendActions.h
+++ b/clang/include/clang/Frontend/FrontendActions.h
@@ -155,19 +155,6 @@
   CreateOutputFile(CompilerInstance &CI, StringRef InFile) override;
 };
 
-class GenerateHeaderModuleAction : public GenerateModuleAction {
-  /// The synthesized module input buffer for the current compilation.
-  std::unique_ptr<llvm::MemoryBuffer> Buffer;
-  std::vector<std::string> ModuleHeaders;
-
-private:
-  bool PrepareToExecuteAction(CompilerInstance &CI) override;
-  bool BeginSourceFileAction(CompilerInstance &CI) override;
-
-  std::unique_ptr<raw_pwrite_stream>
-  CreateOutputFile(CompilerInstance &CI, StringRef InFile) override;
-};
-
 class GenerateHeaderUnitAction : public GenerateModuleAction {
 
 private:
diff --git a/clang/include/clang/Frontend/FrontendOptions.h b/clang/include/clang/Frontend/FrontendOptions.h
--- a/clang/include/clang/Frontend/FrontendOptions.h
+++ b/clang/include/clang/Frontend/FrontendOptions.h
@@ -87,9 +87,6 @@
   /// Generate pre-compiled module from a C++ module interface file.
   GenerateModuleInterface,
 
-  /// Generate pre-compiled module from a set of header files.
-  GenerateHeaderModule,
-
   /// Generate a C++20 header unit module from a header file.
   GenerateHeaderUnit,
 
diff --git a/clang/include/clang/Lex/ModuleMap.h b/clang/include/clang/Lex/ModuleMap.h
--- a/clang/include/clang/Lex/ModuleMap.h
+++ b/clang/include/clang/Lex/ModuleMap.h
@@ -566,9 +566,6 @@
   /// \returns The newly-created module.
   Module *createModuleForInterfaceUnit(SourceLocation Loc, StringRef Name);
 
-  /// Create a header module from the specified list of headers.
-  Module *createHeaderModule(StringRef Name, ArrayRef<Module::Header> Headers);
-
   /// Create a C++20 header unit.
   Module *createHeaderUnit(SourceLocation Loc, StringRef Name,
                            Module::Header H);
diff --git a/clang/lib/Driver/Action.cpp b/clang/lib/Driver/Action.cpp
--- a/clang/lib/Driver/Action.cpp
+++ b/clang/lib/Driver/Action.cpp
@@ -25,7 +25,6 @@
     return "offload";
   case PreprocessJobClass: return "preprocessor";
   case PrecompileJobClass: return "precompiler";
-  case HeaderModulePrecompileJobClass: return "header-module-precompiler";
   case ExtractAPIJobClass:
     return "api-extractor";
   case AnalyzeJobClass: return "analyzer";
@@ -352,13 +351,6 @@
   assert(isa<PrecompileJobAction>((Action*)this) && "invalid action kind");
 }
 
-void HeaderModulePrecompileJobAction::anchor() {}
-
-HeaderModulePrecompileJobAction::HeaderModulePrecompileJobAction(
-    Action *Input, types::ID OutputType, const char *ModuleName)
-    : PrecompileJobAction(HeaderModulePrecompileJobClass, Input, OutputType),
-      ModuleName(ModuleName) {}
-
 void ExtractAPIJobAction::anchor() {}
 
 ExtractAPIJobAction::ExtractAPIJobAction(Action *Inputs, types::ID OutputType)
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -3957,7 +3957,6 @@
           : nullptr;
 
   // Construct the actions to perform.
-  HeaderModulePrecompileJobAction *HeaderModuleAction = nullptr;
   ExtractAPIJobAction *ExtractAPIAction = nullptr;
   ActionList LinkerInputs;
   ActionList MergerInputs;
@@ -4012,16 +4011,6 @@
         break;
       }
 
-      // Each precompiled header file after a module file action is a module
-      // header of that same module file, rather than being compiled to a
-      // separate PCH.
-      if (Phase == phases::Precompile && HeaderModuleAction &&
-          getPrecompiledType(InputType) == types::TY_PCH) {
-        HeaderModuleAction->addModuleHeaderInput(Current);
-        Current = nullptr;
-        break;
-      }
-
       if (Phase == phases::Precompile && ExtractAPIAction) {
         ExtractAPIAction->addHeaderInput(Current);
         Current = nullptr;
@@ -4038,9 +4027,7 @@
       if (NewCurrent == Current)
         continue;
 
-      if (auto *HMA = dyn_cast<HeaderModulePrecompileJobAction>(NewCurrent))
-        HeaderModuleAction = HMA;
-      else if (auto *EAA = dyn_cast<ExtractAPIJobAction>(NewCurrent))
+      if (auto *EAA = dyn_cast<ExtractAPIJobAction>(NewCurrent))
         ExtractAPIAction = EAA;
 
       Current = NewCurrent;
@@ -4524,9 +4511,6 @@
       OutputTy = types::TY_Nothing;
     }
 
-    if (ModName)
-      return C.MakeAction<HeaderModulePrecompileJobAction>(Input, OutputTy,
-                                                           ModName);
     return C.MakeAction<PrecompileJobAction>(Input, OutputTy);
   }
   case phases::Compile: {
@@ -5303,10 +5287,6 @@
   if (JA->getType() == types::TY_dSYM)
     BaseInput = InputInfos[0].getFilename();
 
-  // ... and in header module compilations, which use the module name.
-  if (auto *ModuleJA = dyn_cast<HeaderModulePrecompileJobAction>(JA))
-    BaseInput = ModuleJA->getModuleName();
-
   // Append outputs of offload device jobs to the input list
   if (!OffloadDependencesInputInfo.empty())
     InputInfos.append(OffloadDependencesInputInfo.begin(),
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4539,7 +4539,6 @@
   bool IsHIP = JA.isOffloading(Action::OFK_HIP);
   bool IsHIPDevice = JA.isDeviceOffloading(Action::OFK_HIP);
   bool IsOpenMPDevice = JA.isDeviceOffloading(Action::OFK_OpenMP);
-  bool IsHeaderModulePrecompile = isa<HeaderModulePrecompileJobAction>(JA);
   bool IsExtractAPI = isa<ExtractAPIJobAction>(JA);
   bool IsDeviceOffloadAction = !(JA.isDeviceOffloading(Action::OFK_None) ||
                                  JA.isDeviceOffloading(Action::OFK_Host));
@@ -4554,28 +4553,17 @@
   bool IsUsingLTO = D.isUsingLTO(IsDeviceOffloadAction);
   auto LTOMode = D.getLTOMode(IsDeviceOffloadAction);
 
-  // A header module compilation doesn't have a main input file, so invent a
-  // fake one as a placeholder.
-  const char *ModuleName = [&] {
-    auto *ModuleNameArg = Args.getLastArg(options::OPT_fmodule_name_EQ);
-    return ModuleNameArg ? ModuleNameArg->getValue() : "";
-  }();
-  InputInfo HeaderModuleInput(Inputs[0].getType(), ModuleName, ModuleName);
-
   // Extract API doesn't have a main input file, so invent a fake one as a
   // placeholder.
   InputInfo ExtractAPIPlaceholderInput(Inputs[0].getType(), "extract-api",
                                        "extract-api");
 
   const InputInfo &Input = [&]() -> const InputInfo & {
-    if (IsHeaderModulePrecompile)
-      return HeaderModuleInput;
     if (IsExtractAPI)
       return ExtractAPIPlaceholderInput;
     return Inputs[0];
   }();
 
-  InputInfoList ModuleHeaderInputs;
   InputInfoList ExtractAPIInputs;
   InputInfoList HostOffloadingInputs;
   const InputInfo *CudaDeviceInput = nullptr;
@@ -4583,15 +4571,6 @@
   for (const InputInfo &I : Inputs) {
     if (&I == &Input || I.getType() == types::TY_Nothing) {
       // This is the primary input or contains nothing.
-    } else if (IsHeaderModulePrecompile &&
-               types::getPrecompiledType(I.getType()) == types::TY_PCH) {
-      types::ID Expected = HeaderModuleInput.getType();
-      if (I.getType() != Expected) {
-        D.Diag(diag::err_drv_module_header_wrong_kind)
-            << I.getFilename() << types::getTypeName(I.getType())
-            << types::getTypeName(Expected);
-      }
-      ModuleHeaderInputs.push_back(I);
     } else if (IsExtractAPI) {
       auto ExpectedInputType = ExtractAPIPlaceholderInput.getType();
       if (I.getType() != ExpectedInputType) {
@@ -4779,9 +4758,7 @@
     if (JA.getType() == types::TY_Nothing)
       CmdArgs.push_back("-fsyntax-only");
     else if (JA.getType() == types::TY_ModuleFile)
-      CmdArgs.push_back(IsHeaderModulePrecompile
-                            ? "-emit-header-module"
-                            : "-emit-module-interface");
+      CmdArgs.push_back("-emit-module-interface");
     else if (JA.getType() == types::TY_HeaderUnit)
       CmdArgs.push_back("-emit-header-unit");
     else
@@ -7376,9 +7353,7 @@
   addDashXForInput(Args, Input, CmdArgs);
 
   ArrayRef<InputInfo> FrontendInputs = Input;
-  if (IsHeaderModulePrecompile)
-    FrontendInputs = ModuleHeaderInputs;
-  else if (IsExtractAPI)
+  if (IsExtractAPI)
     FrontendInputs = ExtractAPIInputs;
   else if (Input.isNothing())
     FrontendInputs = {};
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2469,7 +2469,6 @@
 
       {frontend::GenerateModule, OPT_emit_module},
       {frontend::GenerateModuleInterface, OPT_emit_module_interface},
-      {frontend::GenerateHeaderModule, OPT_emit_header_module},
       {frontend::GenerateHeaderUnit, OPT_emit_header_unit},
       {frontend::GeneratePCH, OPT_emit_pch},
       {frontend::GenerateInterfaceStubs, OPT_emit_interface_stubs},
@@ -4129,7 +4128,6 @@
   case frontend::FixIt:
   case frontend::GenerateModule:
   case frontend::GenerateModuleInterface:
-  case frontend::GenerateHeaderModule:
   case frontend::GenerateHeaderUnit:
   case frontend::GeneratePCH:
   case frontend::GenerateInterfaceStubs:
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -265,77 +265,6 @@
   return CI.createDefaultOutputFile(/*Binary=*/true, InFile, "pcm");
 }
 
-bool GenerateHeaderModuleAction::PrepareToExecuteAction(
-    CompilerInstance &CI) {
-  if (!CI.getLangOpts().Modules) {
-    CI.getDiagnostics().Report(diag::err_header_module_requires_modules);
-    return false;
-  }
-
-  auto &Inputs = CI.getFrontendOpts().Inputs;
-  if (Inputs.empty())
-    return GenerateModuleAction::BeginInvocation(CI);
-
-  auto Kind = Inputs[0].getKind();
-
-  // Convert the header file inputs into a single module input buffer.
-  SmallString<256> HeaderContents;
-  ModuleHeaders.reserve(Inputs.size());
-  for (const FrontendInputFile &FIF : Inputs) {
-    // FIXME: We should support re-compiling from an AST file.
-    if (FIF.getKind().getFormat() != InputKind::Source || !FIF.isFile()) {
-      CI.getDiagnostics().Report(diag::err_module_header_file_not_found)
-          << (FIF.isFile() ? FIF.getFile()
-                           : FIF.getBuffer().getBufferIdentifier());
-      return true;
-    }
-
-    HeaderContents += "#include \"";
-    HeaderContents += FIF.getFile();
-    HeaderContents += "\"\n";
-    ModuleHeaders.push_back(std::string(FIF.getFile()));
-  }
-  Buffer = llvm::MemoryBuffer::getMemBufferCopy(
-      HeaderContents, Module::getModuleInputBufferName());
-
-  // Set that buffer up as our "real" input.
-  Inputs.clear();
-  Inputs.push_back(
-      FrontendInputFile(Buffer->getMemBufferRef(), Kind, /*IsSystem*/ false));
-
-  return GenerateModuleAction::PrepareToExecuteAction(CI);
-}
-
-bool GenerateHeaderModuleAction::BeginSourceFileAction(
-    CompilerInstance &CI) {
-  CI.getLangOpts().setCompilingModule(LangOptions::CMK_HeaderModule);
-
-  // Synthesize a Module object for the given headers.
-  auto &HS = CI.getPreprocessor().getHeaderSearchInfo();
-  SmallVector<Module::Header, 16> Headers;
-  for (StringRef Name : ModuleHeaders) {
-    Optional<FileEntryRef> FE = HS.LookupFile(
-        Name, SourceLocation(), /*Angled*/ false, nullptr, nullptr, None,
-        nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
-    if (!FE) {
-      CI.getDiagnostics().Report(diag::err_module_header_file_not_found)
-        << Name;
-      continue;
-    }
-    Headers.push_back(
-        {std::string(Name), std::string(Name), &FE->getFileEntry()});
-  }
-  HS.getModuleMap().createHeaderModule(CI.getLangOpts().CurrentModule, Headers);
-
-  return GenerateModuleAction::BeginSourceFileAction(CI);
-}
-
-std::unique_ptr<raw_pwrite_stream>
-GenerateHeaderModuleAction::CreateOutputFile(CompilerInstance &CI,
-                                             StringRef InFile) {
-  return CI.createDefaultOutputFile(/*Binary=*/true, InFile, "pcm");
-}
-
 bool GenerateHeaderUnitAction::BeginSourceFileAction(CompilerInstance &CI) {
   if (!CI.getLangOpts().CPlusPlusModules) {
     CI.getDiagnostics().Report(diag::err_module_interface_requires_cpp_modules);
diff --git a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
--- a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -65,8 +65,6 @@
     return std::make_unique<GenerateModuleFromModuleMapAction>();
   case GenerateModuleInterface:
     return std::make_unique<GenerateModuleInterfaceAction>();
-  case GenerateHeaderModule:
-    return std::make_unique<GenerateHeaderModuleAction>();
   case GenerateHeaderUnit:
     return std::make_unique<GenerateHeaderUnitAction>();
   case GeneratePCH:            return std::make_unique<GeneratePCHAction>();
diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -899,29 +899,6 @@
   return Result;
 }
 
-Module *ModuleMap::createHeaderModule(StringRef Name,
-                                      ArrayRef<Module::Header> Headers) {
-  assert(LangOpts.CurrentModule == Name && "module name mismatch");
-  assert(!Modules[Name] && "redefining existing module");
-
-  auto *Result =
-      new Module(Name, SourceLocation(), nullptr, /*IsFramework*/ false,
-                 /*IsExplicit*/ false, NumCreatedModules++);
-  Result->Kind = Module::ModuleInterfaceUnit;
-  Modules[Name] = SourceModule = Result;
-
-  for (const Module::Header &H : Headers) {
-    auto *M = new Module(H.NameAsWritten, SourceLocation(), Result,
-                         /*IsFramework*/ false,
-                         /*IsExplicit*/ true, NumCreatedModules++);
-    // Header modules are implicitly 'export *'.
-    M->Exports.push_back(Module::ExportDecl(nullptr, true));
-    addHeader(M, H, NormalHeader);
-  }
-
-  return Result;
-}
-
 Module *ModuleMap::createHeaderUnit(SourceLocation Loc, StringRef Name,
                                     Module::Header H) {
   assert(LangOpts.CurrentModule == Name && "module name mismatch");
diff --git a/clang/test/CXX/cpp/cpp.module/Inputs/attrs.h b/clang/test/CXX/cpp/cpp.module/Inputs/attrs.h
deleted file mode 100644
--- a/clang/test/CXX/cpp/cpp.module/Inputs/attrs.h
+++ /dev/null
@@ -1 +0,0 @@
-#define ATTRS [[ ]]
diff --git a/clang/test/CXX/cpp/cpp.module/Inputs/empty.h b/clang/test/CXX/cpp/cpp.module/Inputs/empty.h
deleted file mode 100644
diff --git a/clang/test/CXX/cpp/cpp.module/p1.cpp b/clang/test/CXX/cpp/cpp.module/p1.cpp
deleted file mode 100644
--- a/clang/test/CXX/cpp/cpp.module/p1.cpp
+++ /dev/null
@@ -1,18 +0,0 @@
-// RUN: %clang_cc1 -std=c++2a -emit-header-module -fmodule-name=attrs -x c++-header %S/Inputs/empty.h %S/Inputs/attrs.h -o %t.pcm
-// RUN: %clang_cc1 -std=c++2a %s -fmodule-file=%t.pcm -E -verify -I%S/Inputs | FileCheck %s
-
-#define SEMI ;
-// expected-error@+1 {{semicolon terminating header import declaration cannot be produced by a macro}}
-import "empty.h" SEMI // CHECK: import attrs.{{.*}};
-
-#define IMPORT import "empty.h"
-IMPORT; // CHECK: import attrs.{{.*}};
-
-#define IMPORT_ANGLED import <empty.h>
-IMPORT_ANGLED; // CHECK: import attrs.{{.*}};
-
-// Ensure that macros only become visible at the semicolon.
-// CHECK: import attrs.{{.*}} ATTRS ;
-import "attrs.h" ATTRS ;
-// CHECK: {{\[\[}} ]] int n;
-ATTRS int n;
diff --git a/clang/test/CXX/cpp/cpp.module/p2.cpp b/clang/test/CXX/cpp/cpp.module/p2.cpp
deleted file mode 100644
--- a/clang/test/CXX/cpp/cpp.module/p2.cpp
+++ /dev/null
@@ -1,32 +0,0 @@
-// RUN: %clang_cc1 -std=c++2a -emit-header-module -fmodule-name=attrs -x c++-header %S/Inputs/empty.h %S/Inputs/attrs.h -o %t.pcm
-// RUN: %clang_cc1 -std=c++2a %s -fmodule-file=%t.pcm -fsyntax-only -verify -I%S/Inputs
-
-template<int> struct import; // expected-note 2{{previous}}
-constexpr struct { int h; } empty = {0};
-struct A;
-struct B;
-struct C;
-template<> struct import<0> {
-  static A a;
-  static B b;
-  static C c;
-};
-
-// OK, not an import-declaration.
-struct A {}
-::import
-<empty.h>::a;
-
-// This is invalid: the tokens after 'import' are a header-name, so cannot be
-// parsed as a template-argument-list.
-struct B {}
-import // expected-error {{redefinition of 'import'}} expected-error {{expected ';'}}
-<empty.h>::b; // (error recovery skips these tokens)
-
-// Likewise, this is ill-formed after the tokens are reconstituted into a
-// header-name token.
-struct C {}
-import // expected-error {{redefinition of 'import'}} expected-error {{expected ';'}}
-<
-empty.h // (error recovery skips these tokens)
->::c;
diff --git a/clang/test/CXX/module/module.interface/p2.cpp b/clang/test/CXX/module/module.interface/p2.cpp
--- a/clang/test/CXX/module/module.interface/p2.cpp
+++ b/clang/test/CXX/module/module.interface/p2.cpp
@@ -1,11 +1,11 @@
 // RUN: rm -rf %t
 // RUN: mkdir -p %t
-// RUN: %clang_cc1 -std=c++2a -x c++-header %S/Inputs/header.h -emit-header-module -fmodule-name=FIXME -o %t/h.pcm
-// RUN: %clang_cc1 -std=c++2a %s -DX_INTERFACE -emit-module-interface -o %t/x.pcm
-// RUN: %clang_cc1 -std=c++2a %s -DY_INTERFACE -emit-module-interface -o %t/y.pcm
-// RUN: %clang_cc1 -std=c++2a %s -DINTERFACE -fmodule-file=%t/x.pcm -fmodule-file=%t/y.pcm -emit-module-interface -o %t/m.pcm
-// RUN: %clang_cc1 -std=c++2a %s -DIMPLEMENTATION -I%S/Inputs -fmodule-file=%t/h.pcm -fmodule-file=%t/m.pcm -verify
-// RUN: %clang_cc1 -std=c++2a %s -DUSER -I%S/Inputs -fmodule-file=%t/h.pcm -fmodule-file=%t/m.pcm -verify
+// RUN: %clang_cc1 -std=c++20 -x c++-header %S/Inputs/header.h -emit-header-unit -o %t/h.pcm
+// RUN: %clang_cc1 -std=c++20 %s -DX_INTERFACE -emit-module-interface -o %t/x.pcm
+// RUN: %clang_cc1 -std=c++20 %s -DY_INTERFACE -emit-module-interface -o %t/y.pcm
+// RUN: %clang_cc1 -std=c++20 %s -DINTERFACE -fmodule-file=%t/x.pcm -fmodule-file=%t/y.pcm -emit-module-interface -o %t/m.pcm
+// RUN: %clang_cc1 -std=c++20 %s -DIMPLEMENTATION -I%S/Inputs -fmodule-file=%t/h.pcm -fmodule-file=%t/m.pcm -verify
+// RUN: %clang_cc1 -std=c++20 %s -DUSER -I%S/Inputs -fmodule-file=%t/h.pcm -fmodule-file=%t/m.pcm -verify
 
 #if defined(X_INTERFACE)
 export module X;
diff --git a/clang/test/Driver/header-module.cpp b/clang/test/Driver/header-module.cpp
deleted file mode 100644
--- a/clang/test/Driver/header-module.cpp
+++ /dev/null
@@ -1,24 +0,0 @@
-// Check compiling a header module to a .pcm file.
-//
-// RUN: %clang -fmodules-ts -fmodule-name=foobar -x c++-header --precompile %S/Inputs/header1.h %S/Inputs/header2.h %S/Inputs/header3.h -o %t.pcm -v 2>&1 | FileCheck %s --check-prefix=CHECK-PRECOMPILE
-//
-// CHECK-PRECOMPILE: -cc1 {{.*}} -emit-header-module
-// CHECK-PRECOMPILE-SAME: -fmodules-ts
-// CHECK-PRECOMPILE-SAME: -fno-implicit-modules
-// CHECK-PRECOMPILE-SAME: -fmodule-name=foobar
-// CHECK-PRECOMPILE-SAME: -o {{.*}}.pcm
-// CHECK-PRECOMPILE-SAME: -x c++-header
-// CHECK-PRECOMPILE-SAME: header1.h
-// CHECK-PRECOMPILE-SAME: header2.h
-// CHECK-PRECOMPILE-SAME: header3.h
-//
-// RUN: %clang -fmodules-ts -fmodule-name=foobar -x c++-header -fsyntax-only %S/Inputs/header1.h %S/Inputs/header2.h %S/Inputs/header3.h -v 2>&1 | FileCheck %s --check-prefix=CHECK-SYNTAX-ONLY
-// CHECK-SYNTAX-ONLY: -cc1 {{.*}} -fsyntax-only
-// CHECK-SYNTAX-ONLY-SAME: -fmodules-ts
-// CHECK-SYNTAX-ONLY-SAME: -fno-implicit-modules
-// CHECK-SYNTAX-ONLY-SAME: -fmodule-name=foobar
-// CHECK-SYNTAX-ONLY-NOT: -o{{ }}
-// CHECK-SYNTAX-ONLY-SAME: -x c++-header
-// CHECK-SYNTAX-ONLY-SAME: header1.h
-// CHECK-SYNTAX-ONLY-SAME: header2.h
-// CHECK-SYNTAX-ONLY-SAME: header3.h
diff --git a/clang/test/Driver/modules.cpp b/clang/test/Driver/modules.cpp
--- a/clang/test/Driver/modules.cpp
+++ b/clang/test/Driver/modules.cpp
@@ -39,37 +39,4 @@
 // RUN: cp %s %t/module.cppm
 // RUN: %clang -std=c++2a --precompile %t/module.cppm -o %t/module.pcm -v 2>&1 | FileCheck %s --check-prefix=CHECK-PRECOMPILE
 
-// Check compiling a header unit to a .pcm file.
-//
-// RUN: echo '#define FOO BAR' > %t/foo.h
-// RUN: %clang -std=c++2a --precompile -x c++-header %t/foo.h -fmodule-name=header -o %t/foo.pcm -v 2>&1 | FileCheck %s --check-prefix=CHECK-HEADER-UNIT
-//
-// CHECK-HEADER-UNIT: -cc1
-// CHECK-HEADER-UNIT-SAME: -emit-header-module
-// CHECK-HEADER-UNIT-SAME: -fmodule-name=header
-// CHECK-HEADER-UNIT-SAME: -o {{.*}}foo.pcm
-// CHECK-HEADER-UNIT-SAME: -x c++-header
-// CHECK-HEADER-UNIT-SAME: foo.h
-
-// Check use of header unit.
-//
-// RUN: %clang -std=c++2a -fmodule-file=%t/module.pcm -fmodule-file=%t/foo.pcm -I%t -DIMPORT -Dexport= %s -E -o - -v 2>&1 | FileCheck %s --check-prefix=CHECK-HEADER-UNIT-USE
-//
-// CHECK-HEADER-UNIT-USE: -cc1
-// CHECK-HEADER-UNIT-USE: -E
-// CHECK-HEADER-UNIT-USE: -fmodule-file={{.*}}module.pcm
-// CHECK-HEADER-UNIT-USE: -fmodule-file={{.*}}foo.pcm
-
-// Note, we use -Dexport= to make this a module implementation unit when building the implementation.
 export module foo;
-
-#ifdef IMPORT
-// CHECK-HEADER-UNIT-USE: FOO;
-FOO;
-
-// CHECK-HEADER-UNIT-USE: import header.{{.*}}foo.h{{.*}};
-import "foo.h";
-
-// CHECK-HEADER-UNIT-USE: BAR;
-FOO;
-#endif
diff --git a/clang/test/Misc/serialized-diags-emit-header-module-misconfig.c b/clang/test/Misc/serialized-diags-emit-header-module-misconfig.c
deleted file mode 100644
--- a/clang/test/Misc/serialized-diags-emit-header-module-misconfig.c
+++ /dev/null
@@ -1,4 +0,0 @@
-// RUN: rm -rf %t && mkdir %t
-// RUN: not %clang_cc1 -emit-header-module %s -o %t/out.pcm -serialize-diagnostic-file %t/diag 2>&1 | FileCheck %s
-
-// CHECK: error: header module compilation requires '-fmodules', '-std=c++20', or '-fmodules-ts'
diff --git a/clang/test/Modules/no-module-map.cpp b/clang/test/Modules/no-module-map.cpp
deleted file mode 100644
--- a/clang/test/Modules/no-module-map.cpp
+++ /dev/null
@@ -1,48 +0,0 @@
-// RUN: %clang_cc1 -fmodules-ts -fmodule-name=ab -x c++-header %S/Inputs/no-module-map/a.h %S/Inputs/no-module-map/b.h -emit-header-module -o %t.pcm
-// RUN: %clang_cc1 -fmodules-ts -fmodule-file=%t.pcm %s -I%S/Inputs/no-module-map -verify
-// RUN: %clang_cc1 -fmodules-ts -fmodule-file=%t.pcm %s -I%S/Inputs/no-module-map -verify -DA
-// RUN: %clang_cc1 -fmodules-ts -fmodule-file=%t.pcm %s -I%S/Inputs/no-module-map -verify -DB
-// RUN: %clang_cc1 -fmodules-ts -fmodule-file=%t.pcm %s -I%S/Inputs/no-module-map -verify -DA -DB
-
-// RUN: %clang_cc1 -E %t.pcm -o - | FileCheck %s
-// RUN: %clang_cc1 -frewrite-imports -E %t.pcm -o - | FileCheck %s
-// CHECK: # {{.*}}a.h
-// CHECK: # {{.*}}b.h
-
-#ifdef B
-// expected-no-diagnostics
-#endif
-
-#ifdef A
-#include "a.h"
-#endif
-
-#ifdef B
-#include "b.h"
-#endif
-
-#if defined(A) || defined(B)
-#ifndef A_H
-#error A_H should be defined
-#endif
-#else
-#ifdef A_H
-#error A_H should not be defined
-#endif
-// expected-error@+3 {{must be imported from}}
-// expected-note@* {{declaration}}
-#endif
-void use_a() { a(); }
-
-#if defined(B)
-#ifndef B_H
-#error B_H should be defined
-#endif
-#else
-#ifdef B_H
-#error B_H should not be defined
-#endif
-// expected-error@+3 {{must be imported from}}
-// expected-note@* {{declaration}}
-#endif
-void use_b() { b(); }