If the special target .MAKEFILEDEPS exists, then enable the

"remaking makefiles" feature.  Otherwise, follow traditional Pmake behavior.
(hash table will be regenerated and committed follow this commit)

usr.bin/make/globals.h

@@ -78,6 +78,7 @@ extern Boolean	beVerbose;	/* True if should print extra cruft */
 extern Boolean	noExecute;	/* True if should execute nothing */
 extern Boolean	allPrecious;	/* True if every target is precious */
 extern Boolean	is_posix;	/* .POSIX target seen */
+extern Boolean	mfAutoDeps;	/* .MAKEFILEDEPS target seen */
 
 /* True if should continue on unaffected portions of the graph
  * when have an error in one portion */

usr.bin/make/main.c

@@ -123,6 +123,7 @@ Lst create = Lst_Initializer(create);
 
 Boolean		allPrecious;	/* .PRECIOUS given on line by itself */
 Boolean		is_posix;	/* .POSIX target seen */
+Boolean		mfAutoDeps;	/* .MAKEFILEDEPS target seen */
 Boolean		beSilent;	/* -s flag */
 Boolean		beVerbose;	/* -v flag */
 Boolean		compatMake;	/* -B argument */
@@ -1252,7 +1253,7 @@ main(int argc, char **argv)
 		 */
 		Lst targs = Lst_Initializer(targs);
 
-		if (!is_posix) {
+		if (!is_posix && mfAutoDeps) {
 			/*
 			 * Check if any of the makefiles are out-of-date.
 			 */

usr.bin/make/make.1

@@ -1312,6 +1312,11 @@ explicitly, or implicitly when
 .Nm
 selects the default target, to give the user a way to refer to the default
 target on the command line.
+.It Ic .MAKEFILEDEPS
+Enable the
+.Dq Li Remaking Makefiles
+functionality.
+See below.
 .It Ic .MAKEFLAGS
 This target provides a way to specify flags for
 .Nm
@@ -1381,6 +1386,10 @@ Apply the
 attribute to any specified sources.
 Targets with this attribute are always
 considered to be out of date.
+.It Ic .POSIX
+Adjust
+.Mn 's
+behavior to match the applicable POSIX specifications.
 .It Ic .PRECIOUS
 Apply the
 .Ic .PRECIOUS
@@ -1544,6 +1553,13 @@ Several flags can be specified on a single
 target by seperating them with blanks.
 .El
 .Sh REMAKING MAKEFILES
+If the special target
+.Ic .MAKEFILEDEPS
+exists in the Makefile,
+.Nm
+enables the
+.Dq Li Remaking Makefiles
+feature.
 After reading Makefile and all the files that are included using
 .Ic .include
 or

usr.bin/make/parse.c

@@ -168,6 +168,7 @@ typedef enum {
 	ExPath,		/* .PATH */
 	Phony,		/* .PHONY */
 	Posix,		/* .POSIX */
+	MakefileDeps,	/* .MAKEFILEDEPS */
 	Precious,	/* .PRECIOUS */
 	ExShell,	/* .SHELL */
 	Silent,		/* .SILENT */
@@ -213,6 +214,7 @@ static const struct keyword {
 	{ ".LIBS",		Libs,		0 },
 	{ ".MAIN",		Main,		0 },
 	{ ".MAKE",		Attribute,	OP_MAKE },
+	{ ".MAKEFILEDEPS",	MakefileDeps,	0 },
 	{ ".MAKEFLAGS",		MFlags,		0 },
 	{ ".MFLAGS",		MFlags,		0 },
 	{ ".NOTMAIN",		Attribute,	OP_NOTMAIN },
@@ -1069,6 +1071,9 @@ ParseDoDependency(char *line)
 			LST_FOREACH(ln, &paths)
 			Path_Clear(Lst_Datum(ln));
 			break;
+		  case MakefileDeps:
+			mfAutoDeps = TRUE;
+			break;
 		  case Posix:
 			is_posix = TRUE;
 			Var_Set("%POSIX", "1003.2", VAR_GLOBAL);