diff --git a/clang/include/clang/Basic/OpenACCKinds.h b/clang/include/clang/Basic/OpenACCKinds.h
index 938385679e3ab..8d52e13ad1358 100644
--- a/clang/include/clang/Basic/OpenACCKinds.h
+++ b/clang/include/clang/Basic/OpenACCKinds.h
@@ -494,7 +494,7 @@ inline StreamTy &printOpenACCClauseKind(StreamTy &Out, OpenACCClauseKind K) {
 
   case OpenACCClauseKind::Shortloop:
     llvm_unreachable("Shortloop shouldn't be generated in clang");
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case OpenACCClauseKind::Invalid:
     return Out << "<invalid>";
   }
diff --git a/clang/include/clang/ExtractAPI/API.h b/clang/include/clang/ExtractAPI/API.h
index 1ace535686a3e..bea5416a626b9 100644
--- a/clang/include/clang/ExtractAPI/API.h
+++ b/clang/include/clang/ExtractAPI/API.h
@@ -618,17 +618,17 @@ struct TagRecord : APIRecord, RecordContext {
   static bool classofKind(RecordKind K) {
     switch (K) {
     case RK_Enum:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_Struct:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_Union:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_CXXClass:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_ClassTemplate:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_ClassTemplateSpecialization:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_ClassTemplatePartialSpecialization:
       return true;
     default:
@@ -704,15 +704,15 @@ struct RecordRecord : TagRecord {
   static bool classofKind(RecordKind K) {
     switch (K) {
     case RK_Struct:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_Union:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_CXXClass:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_ClassTemplate:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_ClassTemplateSpecialization:
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case RK_ClassTemplatePartialSpecialization:
       return true;
     default:
diff --git a/clang/lib/CodeGen/TargetBuiltins/ARM.cpp b/clang/lib/CodeGen/TargetBuiltins/ARM.cpp
index 82b71e398dcc9..2429a430433d7 100644
--- a/clang/lib/CodeGen/TargetBuiltins/ARM.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/ARM.cpp
@@ -7795,7 +7795,7 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
   }
   case NEON::BI__builtin_neon_vcvt1_low_bf16_mf8_fpm:
     ExtractLow = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vcvt1_bf16_mf8_fpm:
   case NEON::BI__builtin_neon_vcvt1_high_bf16_mf8_fpm:
     return EmitFP8NeonCvtCall(Intrinsic::aarch64_neon_fp8_cvtl1,
@@ -7803,7 +7803,7 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
                               Ops[0]->getType(), ExtractLow, Ops, E, "vbfcvt1");
   case NEON::BI__builtin_neon_vcvt2_low_bf16_mf8_fpm:
     ExtractLow = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vcvt2_bf16_mf8_fpm:
   case NEON::BI__builtin_neon_vcvt2_high_bf16_mf8_fpm:
     return EmitFP8NeonCvtCall(Intrinsic::aarch64_neon_fp8_cvtl2,
@@ -7811,7 +7811,7 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
                               Ops[0]->getType(), ExtractLow, Ops, E, "vbfcvt2");
   case NEON::BI__builtin_neon_vcvt1_low_f16_mf8_fpm:
     ExtractLow = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vcvt1_f16_mf8_fpm:
   case NEON::BI__builtin_neon_vcvt1_high_f16_mf8_fpm:
     return EmitFP8NeonCvtCall(Intrinsic::aarch64_neon_fp8_cvtl1,
@@ -7819,7 +7819,7 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
                               Ops[0]->getType(), ExtractLow, Ops, E, "vbfcvt1");
   case NEON::BI__builtin_neon_vcvt2_low_f16_mf8_fpm:
     ExtractLow = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vcvt2_f16_mf8_fpm:
   case NEON::BI__builtin_neon_vcvt2_high_f16_mf8_fpm:
     return EmitFP8NeonCvtCall(Intrinsic::aarch64_neon_fp8_cvtl2,
@@ -7854,7 +7854,7 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
   case NEON::BI__builtin_neon_vdot_lane_f16_mf8_fpm:
   case NEON::BI__builtin_neon_vdotq_lane_f16_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vdot_laneq_f16_mf8_fpm:
   case NEON::BI__builtin_neon_vdotq_laneq_f16_mf8_fpm:
     return EmitFP8NeonFDOTCall(Intrinsic::aarch64_neon_fp8_fdot2_lane,
@@ -7866,7 +7866,7 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
   case NEON::BI__builtin_neon_vdot_lane_f32_mf8_fpm:
   case NEON::BI__builtin_neon_vdotq_lane_f32_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vdot_laneq_f32_mf8_fpm:
   case NEON::BI__builtin_neon_vdotq_laneq_f32_mf8_fpm:
     return EmitFP8NeonFDOTCall(Intrinsic::aarch64_neon_fp8_fdot4_lane,
@@ -7898,37 +7898,37 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
                            "vmlall");
   case NEON::BI__builtin_neon_vmlalbq_lane_f16_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vmlalbq_laneq_f16_mf8_fpm:
     return EmitFP8NeonFMLACall(Intrinsic::aarch64_neon_fp8_fmlalb_lane,
                                ExtendLaneArg, HalfTy, Ops, E, "vmlal_lane");
   case NEON::BI__builtin_neon_vmlaltq_lane_f16_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vmlaltq_laneq_f16_mf8_fpm:
     return EmitFP8NeonFMLACall(Intrinsic::aarch64_neon_fp8_fmlalt_lane,
                                ExtendLaneArg, HalfTy, Ops, E, "vmlal_lane");
   case NEON::BI__builtin_neon_vmlallbbq_lane_f32_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vmlallbbq_laneq_f32_mf8_fpm:
     return EmitFP8NeonFMLACall(Intrinsic::aarch64_neon_fp8_fmlallbb_lane,
                                ExtendLaneArg, FloatTy, Ops, E, "vmlall_lane");
   case NEON::BI__builtin_neon_vmlallbtq_lane_f32_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vmlallbtq_laneq_f32_mf8_fpm:
     return EmitFP8NeonFMLACall(Intrinsic::aarch64_neon_fp8_fmlallbt_lane,
                                ExtendLaneArg, FloatTy, Ops, E, "vmlall_lane");
   case NEON::BI__builtin_neon_vmlalltbq_lane_f32_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vmlalltbq_laneq_f32_mf8_fpm:
     return EmitFP8NeonFMLACall(Intrinsic::aarch64_neon_fp8_fmlalltb_lane,
                                ExtendLaneArg, FloatTy, Ops, E, "vmlall_lane");
   case NEON::BI__builtin_neon_vmlallttq_lane_f32_mf8_fpm:
     ExtendLaneArg = true;
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case NEON::BI__builtin_neon_vmlallttq_laneq_f32_mf8_fpm:
     return EmitFP8NeonFMLACall(Intrinsic::aarch64_neon_fp8_fmlalltt_lane,
                                ExtendLaneArg, FloatTy, Ops, E, "vmlall_lane");
diff --git a/clang/lib/CodeGen/Targets/SystemZ.cpp b/clang/lib/CodeGen/Targets/SystemZ.cpp
index 9b6b72b1dcc05..e50f06c2f548c 100644
--- a/clang/lib/CodeGen/Targets/SystemZ.cpp
+++ b/clang/lib/CodeGen/Targets/SystemZ.cpp
@@ -193,11 +193,11 @@ llvm::Type *SystemZABIInfo::getFPArgumentType(QualType Ty,
     case BuiltinType::Float16:
       if (Size == 16)
         return llvm::Type::getHalfTy(getVMContext());
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case BuiltinType::Float:
       if (Size == 32)
         return llvm::Type::getFloatTy(getVMContext());
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case BuiltinType::Double:
       return llvm::Type::getDoubleTy(getVMContext());
     default:
diff --git a/clang/lib/Interpreter/InterpreterValuePrinter.cpp b/clang/lib/Interpreter/InterpreterValuePrinter.cpp
index 54abfa6dbb9d8..a55b7f5f1a5fc 100644
--- a/clang/lib/Interpreter/InterpreterValuePrinter.cpp
+++ b/clang/lib/Interpreter/InterpreterValuePrinter.cpp
@@ -555,7 +555,7 @@ llvm::Expected<Expr *> Interpreter::convertExprToValue(Expr *E) {
   InterfaceKind Kind = V.computeInterfaceKind(DesugaredTy);
   switch (Kind) {
   case InterfaceKind::WithAlloc:
-    LLVM_FALLTHROUGH;
+    [[fallthrough]];
   case InterfaceKind::CopyArray: {
     // __clang_Interpreter_SetValueWithAlloc.
     ExprResult AllocCall =
diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp
index 8aebf53c0e76f..db14349430933 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -1265,7 +1265,7 @@ checkExprLifetimeImpl(Sema &SemaRef, const InitializedEntity *InitEntity,
       return true;
     case NotGSLPointer:
       IsGslPtrValueFromGslTempOwner = false;
-      LLVM_FALLTHROUGH;
+      [[fallthrough]];
     case Report:
       break;
     }