diff --git a/llvm/tools/llvm-reduce/DeltaManager.h b/llvm/tools/llvm-reduce/DeltaManager.h
index b72e5604bd54a..c1445a7da769f 100644
--- a/llvm/tools/llvm-reduce/DeltaManager.h
+++ b/llvm/tools/llvm-reduce/DeltaManager.h
@@ -1,4 +1,4 @@
-//===- DeltaManager.h - Runs Delta Passes to reduce Input -----------------===//
+//===- DeltaManager.h - Runs Delta Passes to reduce Input -------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/ReducerWorkItem.h b/llvm/tools/llvm-reduce/ReducerWorkItem.h
index 7dd578687f855..ce73d4f18a136 100644
--- a/llvm/tools/llvm-reduce/ReducerWorkItem.h
+++ b/llvm/tools/llvm-reduce/ReducerWorkItem.h
@@ -1,4 +1,4 @@
-//===- ReducerWorkItem.h - Wrapper for Module and MachineFunction ---------===//
+//===- ReducerWorkItem.h - Wrapper for Module -------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/Delta.h b/llvm/tools/llvm-reduce/deltas/Delta.h
index 76aaf25044826..f8c8ede3f1550 100644
--- a/llvm/tools/llvm-reduce/deltas/Delta.h
+++ b/llvm/tools/llvm-reduce/deltas/Delta.h
@@ -1,4 +1,4 @@
-//===- Delta.h - Delta Debugging Algorithm Implementation -----------------===//
+//===- Delta.h - Delta Debugging Algorithm Implementation -------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceAliases.h b/llvm/tools/llvm-reduce/deltas/ReduceAliases.h
index 0660efe5e9d5b..82b4d3e7c07a2 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceAliases.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceAliases.h
@@ -1,4 +1,4 @@
-//===- ReduceAliases.h - Specialized Delta Pass ---------------------------===//
+//===- ReduceAliases.h - Specialized Delta Pass -----------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceArguments.h b/llvm/tools/llvm-reduce/deltas/ReduceArguments.h
index 228409d3ca3c1..5adcfe89266bc 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceArguments.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceArguments.h
@@ -1,4 +1,4 @@
-//===- ReduceArguments.h - Specialized Delta Pass -------------------------===//
+//===- ReduceArguments.h - Specialized Delta Pass ---------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceAttributes.h b/llvm/tools/llvm-reduce/deltas/ReduceAttributes.h
index 375e764df0342..a2e9955ac5bb4 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceAttributes.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceAttributes.h
@@ -1,4 +1,4 @@
-//===- ReduceAttributes.h - Specialized Delta Pass ------------------------===//
+//===- ReduceAttributes.h - Specialized Delta Pass --------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.h b/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.h
index 49385527cb808..02fe127b9bfe0 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceBasicBlocks.h
@@ -1,4 +1,4 @@
-//===- ReduceArguments.h - Specialized Delta Pass -------------------------===//
+//===- ReduceArguments.h - Specialized Delta Pass ---------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceFunctionBodies.h b/llvm/tools/llvm-reduce/deltas/ReduceFunctionBodies.h
index bfe701b588b61..1713dfcf0826e 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceFunctionBodies.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceFunctionBodies.h
@@ -1,4 +1,4 @@
-//===- ReduceFunctionBodies.h - Specialized Delta Pass --------------------===//
+//===- ReduceFunctionBodies.h - Specialized Delta Pass ----------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceFunctions.h b/llvm/tools/llvm-reduce/deltas/ReduceFunctions.h
index f5bc83b9a1e20..d3ff0d9511289 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceFunctions.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceFunctions.h
@@ -1,4 +1,4 @@
-//===- ReduceFunctions.h - Specialized Delta Pass -------------------------===//
+//===- ReduceFunctions.h - Specialized Delta Pass ---------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceGlobalObjects.h b/llvm/tools/llvm-reduce/deltas/ReduceGlobalObjects.h
index 7224b9bfbd5f9..35c38a9ecf212 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceGlobalObjects.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceGlobalObjects.h
@@ -1,4 +1,4 @@
-//===- ReduceGlobalObjects.h ----------------------------------------------===//
+//===- ReduceGlobalObjects.h ------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.h b/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.h
index ea32a6c20bcbd..19c0707936528 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceGlobalValues.h
@@ -1,4 +1,4 @@
-//===- ReduceGlobalValues.h - Specialized Delta Pass ----------------------===//
+//===- ReduceGlobalValues.h - Specialized Delta Pass ------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceGlobalVarInitializers.h b/llvm/tools/llvm-reduce/deltas/ReduceGlobalVarInitializers.h
index 0f5f22ad43afd..318b29b6ca5e4 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceGlobalVarInitializers.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceGlobalVarInitializers.h
@@ -1,4 +1,4 @@
-//===- reduceGlobalsInitializersDeltaPass.h - Specialized Delta Pass ------===//
+//===- ReduceGlobalVarInitializers.h ----------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceGlobalVars.h b/llvm/tools/llvm-reduce/deltas/ReduceGlobalVars.h
index fe7813c538533..1198dceb45368 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceGlobalVars.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceGlobalVars.h
@@ -1,4 +1,4 @@
-//===- ReduceGlobalVars.h - Specialized Delta Pass ------------------------===//
+//===- ReduceGlobalVars.h - Specialized Delta Pass --------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlagsMIR.h b/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlagsMIR.h
index a211994bc83b1..a5a34d275e2f0 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlagsMIR.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceInstructionFlagsMIR.h
@@ -1,4 +1,4 @@
-//===- ReduceInstructionFlagsMIR.h  - Specialized Delta Pass --------------===//
+//===- ReduceInstructionFlagsMIR.h  -----------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceInstructions.h b/llvm/tools/llvm-reduce/deltas/ReduceInstructions.h
index be568f184969b..8c13a02cb98f3 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceInstructions.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceInstructions.h
@@ -1,4 +1,4 @@
-//===- ReduceArguments.h - Specialized Delta Pass -------------------------===//
+//===- ReduceInstructions.h -------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.h b/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.h
index a59f1aa8f0d67..70e0ac5fcf37f 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.h
@@ -1,4 +1,4 @@
-//===- ReduceInstructionsMIR.h  - Specialized Delta Pass ------------------===//
+//===- ReduceInstructionsMIR.h  - Specialized Delta Pass --------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceMetadata.h b/llvm/tools/llvm-reduce/deltas/ReduceMetadata.h
index 6efc3f5598d69..2bc28a9814187 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceMetadata.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceMetadata.h
@@ -1,4 +1,4 @@
-//===- ReduceMetadata.h - Specialized Delta Pass --------------------------===//
+//===- ReduceMetadata.h - Specialized Delta Pass ----------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceModuleData.h b/llvm/tools/llvm-reduce/deltas/ReduceModuleData.h
index 972c53460d760..960fe8c6d3a6d 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceModuleData.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceModuleData.h
@@ -1,4 +1,4 @@
-//===- ReduceModuleData.h --------------------------------------------===//
+//===- ReduceModuleData.h ---------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceOperandBundles.h b/llvm/tools/llvm-reduce/deltas/ReduceOperandBundles.h
index d07e0218595b0..390b029242536 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceOperandBundles.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceOperandBundles.h
@@ -1,4 +1,4 @@
-//===- ReduceOperandBundes.h - Specialized Delta Pass ---------------------===//
+//===- ReduceOperandBundes.h ------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceOperands.h b/llvm/tools/llvm-reduce/deltas/ReduceOperands.h
index 034f49b8e4c51..b4a18998f8e20 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceOperands.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceOperands.h
@@ -1,4 +1,4 @@
-//===----------------------------------------------------------------------===//
+//===------------------------------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceOperandsSkip.h b/llvm/tools/llvm-reduce/deltas/ReduceOperandsSkip.h
index 79ee46235e6d7..79897011639a2 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceOperandsSkip.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceOperandsSkip.h
@@ -1,4 +1,4 @@
-//===----------------------------------------------------------------------===//
+//===------------------------------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.h b/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.h
index 2bff39361675e..23043dd60b6ff 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceOperandsToArgs.h
@@ -1,4 +1,4 @@
-//===----------------------------------------------------------------------===//
+//===------------------------------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceSpecialGlobals.h b/llvm/tools/llvm-reduce/deltas/ReduceSpecialGlobals.h
index c0f3f9ee337d8..d17790529e06b 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceSpecialGlobals.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceSpecialGlobals.h
@@ -1,4 +1,4 @@
-//===- ReduceSpecialGlobals.h - Specialized Delta Pass --------------------===//
+//===- ReduceSpecialGlobals.h - Specialized Delta Pass ----------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceUsingSimplifyCFG.h b/llvm/tools/llvm-reduce/deltas/ReduceUsingSimplifyCFG.h
index 0105ad2b29744..56cd15a1a1355 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceUsingSimplifyCFG.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceUsingSimplifyCFG.h
@@ -1,4 +1,4 @@
-//===- ReduceUsingSimplifyCFG.h - Specialized Delta Pass ------------------===//
+//===- ReduceUsingSimplifyCFG.h - Specialized Delta Pass --------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/RunIRPasses.h b/llvm/tools/llvm-reduce/deltas/RunIRPasses.h
index 603363bdfcec9..f1d4140d5b57f 100644
--- a/llvm/tools/llvm-reduce/deltas/RunIRPasses.h
+++ b/llvm/tools/llvm-reduce/deltas/RunIRPasses.h
@@ -1,4 +1,4 @@
-//===- RunIRPasses.h ------------------------------------------------------===//
+//===- RunIRPasses.h --------------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
diff --git a/llvm/tools/llvm-reduce/deltas/Utils.h b/llvm/tools/llvm-reduce/deltas/Utils.h
index 43c38f831b179..91041e2517d52 100644
--- a/llvm/tools/llvm-reduce/deltas/Utils.h
+++ b/llvm/tools/llvm-reduce/deltas/Utils.h
@@ -1,4 +1,4 @@
-//===- Utils.h - llvm-reduce utility functions ----------------------------===//
+//===- Utils.h - llvm-reduce utility functions ------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.