diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -678,4 +678,8 @@
 def err_drv_invalid_empty_dxil_validator_version : Error<
   "invalid validator version : %0\n"
   "If validator major version is 0, minor version must also be 0.">;
+
+def warn_drv_sarif_format_unstable : Warning<
+  "diagnostic formatting in SARIF mode is currently unstable">,
+  InGroup<DiagGroup<"sarif-format-unstable">>;
 }
diff --git a/clang/include/clang/Basic/DiagnosticOptions.h b/clang/include/clang/Basic/DiagnosticOptions.h
--- a/clang/include/clang/Basic/DiagnosticOptions.h
+++ b/clang/include/clang/Basic/DiagnosticOptions.h
@@ -74,7 +74,7 @@
   friend class CompilerInvocation;
 
 public:
-  enum TextDiagnosticFormat { Clang, MSVC, Vi };
+  enum TextDiagnosticFormat { Clang, MSVC, Vi, SARIF };
 
   // Default values.
   enum {
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
@@ -5580,8 +5580,8 @@
 
 def fdiagnostics_format : Separate<["-"], "fdiagnostics-format">,
   HelpText<"Change diagnostic formatting to match IDE and command line tools">,
-  Values<"clang,msvc,vi">,
-  NormalizedValuesScope<"DiagnosticOptions">, NormalizedValues<["Clang", "MSVC", "Vi"]>,
+  Values<"clang,msvc,vi,sarif">,
+  NormalizedValuesScope<"DiagnosticOptions">, NormalizedValues<["Clang", "MSVC", "Vi", "SARIF"]>,
   MarshallingInfoEnum<DiagnosticOpts<"Format">, "Clang">;
 def fdiagnostics_show_category : Separate<["-"], "fdiagnostics-show-category">,
   HelpText<"Print diagnostic category">,
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
@@ -4006,6 +4006,9 @@
   if (const Arg *A = Args.getLastArg(options::OPT_fdiagnostics_format_EQ)) {
     CmdArgs.push_back("-fdiagnostics-format");
     CmdArgs.push_back(A->getValue());
+    if (StringRef(A->getValue()) == "sarif") {
+      D.Diag(diag::warn_drv_sarif_format_unstable);
+    }
   }
 
   if (const Arg *A = Args.getLastArg(
diff --git a/clang/lib/Frontend/TextDiagnostic.cpp b/clang/lib/Frontend/TextDiagnostic.cpp
--- a/clang/lib/Frontend/TextDiagnostic.cpp
+++ b/clang/lib/Frontend/TextDiagnostic.cpp
@@ -815,6 +815,7 @@
 
   emitFilename(PLoc.getFilename(), Loc.getManager());
   switch (DiagOpts->getFormat()) {
+  case DiagnosticOptions::SARIF:
   case DiagnosticOptions::Clang:
     if (DiagOpts->ShowLine)
       OS << ':' << LineNo;
@@ -837,6 +838,7 @@
       OS << ColNo;
     }
   switch (DiagOpts->getFormat()) {
+  case DiagnosticOptions::SARIF:
   case DiagnosticOptions::Clang:
   case DiagnosticOptions::Vi:    OS << ':';    break;
   case DiagnosticOptions::MSVC:
diff --git a/clang/test/Driver/fdiagnostics-format-sarif.cpp b/clang/test/Driver/fdiagnostics-format-sarif.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/fdiagnostics-format-sarif.cpp
@@ -0,0 +1,2 @@
+// RUN: %clang -fsyntax-only -fdiagnostics-format=sarif %s -### 2>&1 | FileCheck %s --check-prefix=WARN
+// WARN: warning: diagnostic formatting in SARIF mode is currently unstable [-Wsarif-format-unstable]