diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index 699a0be7203683..8eb010eae2659d 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -1014,9 +1014,9 @@ Include path management
 
 Flags controlling how ``#include``\s are resolved to files.
 
-.. option:: -I<dir>, --include-directory <dir>, --include-directory=<dir>
+.. option:: -I<dir>, --include-directory <arg>, --include-directory=<arg>
 
-Add directory <dir> to the list of include files search paths. If there are multiple -I options, these directories are searched in the order they are given before the standard system directories are searched. If the same directory is in the SYSTEM include search paths, for example if also specified with -isystem, the -I option will be ignored
+Add directory to include search path. If there are multiple -I options, these directories are searched in the order they are given before the standard system directories are searched. If the same directory is in the SYSTEM include search paths, for example if also specified with -isystem, the -I option will be ignored
 
 .. option:: -I-, --include-barrier
 
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 889035a0815e01..16051934c1e0b1 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -395,7 +395,12 @@ def I_ : Flag<["-"], "I-">, Group<I_Group>,
              "remove current directory from include path">;
 def I : JoinedOrSeparate<["-"], "I">, Group<I_Group>,
     Flags<[CC1Option,CC1AsOption]>, MetaVarName<"<dir>">,
-    HelpText<"Add directory to include search path">;
+    HelpText<"Add directory to include search path. If there are multiple -I "
+             "options, these directories are searched in the order they are "
+             "given before the standard system directories are searched. "
+             "If the same directory is in the SYSTEM include search paths, for "
+             "example if also specified with -isystem, the -I option will be "
+             "ignored">;
 def L : JoinedOrSeparate<["-"], "L">, Flags<[RenderJoined]>, Group<Link_Group>,
     MetaVarName<"<dir>">, HelpText<"Add directory to library search path">;
 def MD : Flag<["-"], "MD">, Group<M_Group>,
@@ -1244,7 +1249,7 @@ def finline_functions : Flag<["-"], "finline-functions">, Group<f_clang_Group>,
 def finline_hint_functions: Flag<["-"], "finline-hint-functions">, Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Inline functions which are (explicitly or implicitly) marked inline">;
 def finline : Flag<["-"], "finline">, Group<clang_ignored_f_Group>;
-def fglobal_isel : Flag<["-"], "fglobal-isel">, Group<f_clang_Group>, 
+def fglobal_isel : Flag<["-"], "fglobal-isel">, Group<f_clang_Group>,
   HelpText<"Enables the global instruction selector">;
 def fexperimental_isel : Flag<["-"], "fexperimental-isel">, Group<f_clang_Group>,
   Alias<fglobal_isel>;