diff --git a/include/clang/Basic/LangOptions.def b/include/clang/Basic/LangOptions.def
index 03561961dd218b91e5050d32fa8c039cb62e4663..7a2bf24d3ae7c109a2cfc6559e136c33ce5c6207 100644
--- a/include/clang/Basic/LangOptions.def
+++ b/include/clang/Basic/LangOptions.def
@@ -142,6 +142,7 @@ BENIGN_LANGOPT(EmitAllDecls      , 1, 0, "emitting all declarations")
 LANGOPT(MathErrno         , 1, 1, "errno in math functions")
 BENIGN_LANGOPT(HeinousExtensions , 1, 0, "extensions that we really don't like and may be ripped out at any time")
 LANGOPT(Modules           , 1, 0, "modules extension to C")
+LANGOPT(ModulesTS         , 1, 0, "C++ Modules TS")
 BENIGN_LANGOPT(CompilingModule, 1, 0, "compiling a module interface")
 COMPATIBLE_LANGOPT(ModulesDeclUse    , 1, 0, "require declaration of module uses")
 BENIGN_LANGOPT(ModulesSearchAll  , 1, 1, "searching even non-imported modules to find unresolved references")
diff --git a/include/clang/Basic/TokenKinds.def b/include/clang/Basic/TokenKinds.def
index 882c6e4cac2c73f071b3efa39dd30e1b6f8b4d83..82cb6c21f9ec779280f26dc03cd5f95333f93f46 100644
--- a/include/clang/Basic/TokenKinds.def
+++ b/include/clang/Basic/TokenKinds.def
@@ -30,6 +30,9 @@
 #ifndef CONCEPTS_KEYWORD
 #define CONCEPTS_KEYWORD(X) KEYWORD(X,KEYCONCEPTS)
 #endif
+#ifndef MODULES_KEYWORD
+#define MODULES_KEYWORD(X) KEYWORD(X,KEYMODULES)
+#endif
 #ifndef TYPE_TRAIT
 #define TYPE_TRAIT(N,I,K) KEYWORD(I,K)
 #endif
@@ -235,6 +238,8 @@ PUNCTUATOR(caretcaret,            "^^")
 //   KEYCXX11 - This is a C++ keyword introduced to C++ in C++11
 //   KEYCONCEPTS - This is a keyword if the C++ extensions for concepts
 //                 are enabled.
+//   KEYMODULES - This is a keyword if the C++ extensions for modules
+//                are enabled.
 //   KEYGNU   - This is a keyword if GNU extensions are enabled
 //   KEYMS    - This is a keyword if Microsoft extensions are enabled
 //   KEYNOMS18 - This is a keyword that must never be enabled under
@@ -366,6 +371,10 @@ KEYWORD(co_await                    , KEYCOROUTINES)
 KEYWORD(co_return                   , KEYCOROUTINES)
 KEYWORD(co_yield                    , KEYCOROUTINES)
 
+// C++ modules TS keywords
+MODULES_KEYWORD(module)
+MODULES_KEYWORD(import)
+
 // GNU Extensions (in impl-reserved namespace)
 KEYWORD(_Decimal32                  , KEYALL)
 KEYWORD(_Decimal64                  , KEYALL)
diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 1401984c2a3488efeffa4adde3689e88899a8ceb..aa8352204b6f527111ee3caed3a701292f7a75be 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -388,6 +388,8 @@ def ast_dump_filter : Separate<["-"], "ast-dump-filter">,
   HelpText<"Use with -ast-dump or -ast-print to dump/print only AST declaration"
            " nodes having a certain substring in a qualified name. Use"
            " -ast-list to list all filterable declaration node names.">;
+def fmodules_ts : Flag <["-"], "fmodules-ts">, Group<f_Group>,
+  HelpText<"Enable support for the C++ Modules TS">;
 def fno_modules_global_index : Flag<["-"], "fno-modules-global-index">,
   HelpText<"Do not automatically generate or update the global module index">;
 def fno_modules_error_recovery : Flag<["-"], "fno-modules-error-recovery">,
diff --git a/lib/Basic/IdentifierTable.cpp b/lib/Basic/IdentifierTable.cpp
index d6ad0f5c9158d8a598cf1b266297bf8f843e721f..537a2b702d84e167f93e5fe8c78c21a3342fd06f 100644
--- a/lib/Basic/IdentifierTable.cpp
+++ b/lib/Basic/IdentifierTable.cpp
@@ -113,7 +113,8 @@ namespace {
     KEYOBJC2    = 0x20000,
     KEYZVECTOR  = 0x40000,
     KEYCOROUTINES = 0x80000,
-    KEYALL = (0xfffff & ~KEYNOMS18 &
+    KEYMODULES = 0x100000,
+    KEYALL = (0x1fffff & ~KEYNOMS18 &
               ~KEYNOOPENCL) // KEYNOMS18 and KEYNOOPENCL are used to exclude.
   };
 
@@ -147,9 +148,10 @@ static KeywordStatus getKeywordStatus(const LangOptions &LangOpts,
   // We treat bridge casts as objective-C keywords so we can warn on them
   // in non-arc mode.
   if (LangOpts.ObjC2 && (Flags & KEYARC)) return KS_Enabled;
-  if (LangOpts.ConceptsTS && (Flags & KEYCONCEPTS)) return KS_Enabled;
   if (LangOpts.ObjC2 && (Flags & KEYOBJC2)) return KS_Enabled;
+  if (LangOpts.ConceptsTS && (Flags & KEYCONCEPTS)) return KS_Enabled;
   if (LangOpts.Coroutines && (Flags & KEYCOROUTINES)) return KS_Enabled;
+  if (LangOpts.ModulesTS && (Flags & KEYMODULES)) return KS_Enabled;
   if (LangOpts.CPlusPlus && (Flags & KEYCXX11)) return KS_Future;
   return KS_Disabled;
 }
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index eacba7d4e067a7e9f3739bdb10276b2b890a7700..98eb4bb3776d87356e4653bef410f42c33bb1b60 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1873,12 +1873,13 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
     && Opts.OpenCLVersion >= 200);
   Opts.BlocksRuntimeOptional = Args.hasArg(OPT_fblocks_runtime_optional);
   Opts.Coroutines = Args.hasArg(OPT_fcoroutines);
-  Opts.Modules = Args.hasArg(OPT_fmodules);
+  Opts.ModulesTS = Args.hasArg(OPT_fmodules_ts);
+  Opts.Modules = Args.hasArg(OPT_fmodules) || Opts.ModulesTS;
   Opts.ModulesStrictDeclUse = Args.hasArg(OPT_fmodules_strict_decluse);
   Opts.ModulesDeclUse =
       Args.hasArg(OPT_fmodules_decluse) || Opts.ModulesStrictDeclUse;
   Opts.ModulesLocalVisibility =
-      Args.hasArg(OPT_fmodules_local_submodule_visibility);
+      Args.hasArg(OPT_fmodules_local_submodule_visibility) || Opts.ModulesTS;
   Opts.ModulesSearchAll = Opts.Modules &&
     !Args.hasArg(OPT_fno_modules_search_all) &&
     Args.hasArg(OPT_fmodules_search_all);
diff --git a/test/Lexer/modules-ts.cpp b/test/Lexer/modules-ts.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..06be17c536662ada232a89a6625a2979cb5822b8
--- /dev/null
+++ b/test/Lexer/modules-ts.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -fsyntax-only %s
+// RUN: %clang_cc1 -fmodules-ts -DMODULES -fsyntax-only %s
+
+#ifdef MODULES
+#define MODULES_KEYWORD(NAME) _Static_assert(!__is_identifier(NAME), #NAME)
+#else
+#define MODULES_KEYWORD(NAME) _Static_assert(__is_identifier(NAME), #NAME)
+#endif
+
+MODULES_KEYWORD(import);
+MODULES_KEYWORD(module);