diff --git a/clang/include/clang/Basic/DiagnosticOptions.h b/clang/include/clang/Basic/DiagnosticOptions.h
index c4134835b5dec..4b0d45a3ff7c7 100644
--- a/clang/include/clang/Basic/DiagnosticOptions.h
+++ b/clang/include/clang/Basic/DiagnosticOptions.h
@@ -46,20 +46,20 @@ enum class DiagnosticLevelMask : unsigned {
 };
 
 inline DiagnosticLevelMask operator~(DiagnosticLevelMask M) {
-  using UT = std::underlying_type<DiagnosticLevelMask>::type;
+  using UT = std::underlying_type_t<DiagnosticLevelMask>;
   return static_cast<DiagnosticLevelMask>(~static_cast<UT>(M));
 }
 
 inline DiagnosticLevelMask operator|(DiagnosticLevelMask LHS,
                                      DiagnosticLevelMask RHS) {
-  using UT = std::underlying_type<DiagnosticLevelMask>::type;
+  using UT = std::underlying_type_t<DiagnosticLevelMask>;
   return static_cast<DiagnosticLevelMask>(
     static_cast<UT>(LHS) | static_cast<UT>(RHS));
 }
 
 inline DiagnosticLevelMask operator&(DiagnosticLevelMask LHS,
                                      DiagnosticLevelMask RHS) {
-  using UT = std::underlying_type<DiagnosticLevelMask>::type;
+  using UT = std::underlying_type_t<DiagnosticLevelMask>;
   return static_cast<DiagnosticLevelMask>(
     static_cast<UT>(LHS) & static_cast<UT>(RHS));
 }
diff --git a/clang/lib/Basic/DiagnosticOptions.cpp b/clang/lib/Basic/DiagnosticOptions.cpp
index 68571f2cf94fa..12e47ea0231e1 100644
--- a/clang/lib/Basic/DiagnosticOptions.cpp
+++ b/clang/lib/Basic/DiagnosticOptions.cpp
@@ -17,7 +17,7 @@
 namespace clang {
 
 raw_ostream &operator<<(raw_ostream &Out, DiagnosticLevelMask M) {
-  using UT = std::underlying_type<DiagnosticLevelMask>::type;
+  using UT = std::underlying_type_t<DiagnosticLevelMask>;
   return Out << static_cast<UT>(M);
 }