diff --git a/clang/include/clang/Basic/DiagnosticCommentKinds.td b/clang/include/clang/Basic/DiagnosticCommentKinds.td
index beeb23fcb11869c41152d82bc7c014160c51eb85..49781fec9a9cf882b96aba4ac05194ce364289eb 100644
--- a/clang/include/clang/Basic/DiagnosticCommentKinds.td
+++ b/clang/include/clang/Basic/DiagnosticCommentKinds.td
@@ -157,7 +157,8 @@ def warn_verbatim_block_end_without_start : Warning<
   InGroup<Documentation>, DefaultIgnore;
 
 def warn_unknown_comment_command_name : Warning<
-  "unknown command tag name">, InGroup<Documentation>, DefaultIgnore;
+  "unknown command tag name">,
+  InGroup<DocumentationUnknownCommand>, DefaultIgnore;
 
 def warn_correct_comment_command_name : Warning<
   "unknown command tag name '%0'; did you mean '%1'?">,
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index d7d20feb4d143d73c2990e53a824203a1a2e4dd6..d5f777d3d7152d4bc208e750d226d9b481bbf0e9 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -68,7 +68,9 @@ def : DiagGroup<"discard-qual">;
 def : DiagGroup<"div-by-zero">;
 
 def DocumentationHTML : DiagGroup<"documentation-html">;
-def DocumentationPedantic : DiagGroup<"documentation-pedantic">;
+def DocumentationUnknownCommand : DiagGroup<"documentation-unknown-command">;
+def DocumentationPedantic : DiagGroup<"documentation-pedantic",
+                                      [DocumentationUnknownCommand]>;
 def DocumentationDeprecatedSync : DiagGroup<"documentation-deprecated-sync">;
 def Documentation : DiagGroup<"documentation",
                               [DocumentationHTML,