diff --git a/Source/cmIncludeDirectoryCommand.h b/Source/cmIncludeDirectoryCommand.h
index 3b35d55de..cbe344f3c 100644
--- a/Source/cmIncludeDirectoryCommand.h
+++ b/Source/cmIncludeDirectoryCommand.h
@@ -58,13 +58,21 @@ public:
     {
     return
       "  include_directories([AFTER|BEFORE] [SYSTEM] dir1 dir2 ...)\n"
-      "Add the given directories to those searched by the compiler for "
-      "include files. By default the directories are appended onto "
-      "the current list of directories. This default behavior can be "
-      "changed by setting CMAKE_INCLUDE_DIRECTORIES_BEFORE to ON. "
-      "By using BEFORE or AFTER you can select between appending and "
-      "prepending, independent from the default. "
-      "If the SYSTEM option is given the compiler will be told that the "
+      "Add the given directories to those the compiler uses to search "
+      "for include files. "
+      "These directories are added to the directory property "
+      "INCLUDE_DIRECTORIES for the current CMakeLists file. "
+      "They are also added to the target property INCLUDE_DIRECTORIES "
+      "for each target in the current CMakeLists file. "
+      "The target property values are the ones used by the generators."
+      "\n"
+      "By default the directories are appended onto the current list of "
+      "directories. "
+      "This default behavior can be changed by setting "
+      "CMAKE_INCLUDE_DIRECTORIES_BEFORE to ON. "
+      "By using AFTER or BEFORE explicitly, you can select between "
+      "appending and prepending, independent of the default. "
+      "If the SYSTEM option is given, the compiler will be told the "
       "directories are meant as system include directories on some "
       "platforms.";
     }
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 84dc87249..d206d3216 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -3860,9 +3860,22 @@ void cmMakefile::DefineProperties(cmake *cm)
   cm->DefineProperty
     ("INCLUDE_DIRECTORIES", cmProperty::DIRECTORY,
      "List of preprocessor include file search directories.",
-     "This read-only property specifies the list of directories given "
-     "so far to the include_directories command.  "
-     "It is intended for debugging purposes.", false);
+     "This property specifies the list of directories given "
+     "so far to the include_directories command. "
+     "This property exists on directories and targets. "
+     "In addition to accepting values from the include_directories "
+     "command, values may be set directly on any directory or any "
+     "target using the set_property command. "
+     "A target gets its initial value for this property from the value "
+     "of the directory property. "
+     "A directory gets its initial value from its parent directory if "
+     "it has one. "
+     "Both directory and target property values are adjusted by calls "
+     "to the include_directories command."
+     "\n"
+     "The target property values are used by the generators to set "
+     "the include paths for the compiler. "
+     "See also the include_directories command.");
 
   cm->DefineProperty
     ("LINK_DIRECTORIES", cmProperty::DIRECTORY,
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index cd816a699..e618bee41 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -485,6 +485,26 @@ void cmTarget::DefineProperties(cmake *cm)
      "Installing a target with EXCLUDE_FROM_ALL set to true has "
      "undefined behavior.");
 
+  cm->DefineProperty
+    ("INCLUDE_DIRECTORIES", cmProperty::TARGET,
+     "List of preprocessor include file search directories.",
+     "This property specifies the list of directories given "
+     "so far to the include_directories command. "
+     "This property exists on directories and targets. "
+     "In addition to accepting values from the include_directories "
+     "command, values may be set directly on any directory or any "
+     "target using the set_property command. "
+     "A target gets its initial value for this property from the value "
+     "of the directory property. "
+     "A directory gets its initial value from its parent directory if "
+     "it has one. "
+     "Both directory and target property values are adjusted by calls "
+     "to the include_directories command."
+     "\n"
+     "The target property values are used by the generators to set "
+     "the include paths for the compiler. "
+     "See also the include_directories command.");
+
   cm->DefineProperty
     ("INSTALL_NAME_DIR", cmProperty::TARGET,
      "Mac OSX directory name for installed targets.",