diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e4b54744f9e..0fd205f5b13 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2002-04-26  Richard Henderson  <rth@redhat.com>
+
+	* c-parse.in (malloced_yyss, malloced_yyvs): New.
+	(yyoverflow): Re-add.  Set them.
+	(free_parser_stacks): New.
+	* c-common.h: Declare it.
+	* c-lex.c (c_common_parse_file): Call it.
+
 2002-04-26  Richard Henderson  <rth@redhat.com>
 
 	* cfgrtl.c (tidy_fallthru_edge): Don't use next_real_insn
diff --git a/gcc/c-common.h b/gcc/c-common.h
index 873fa4a2919..a8439d4966a 100644
--- a/gcc/c-common.h
+++ b/gcc/c-common.h
@@ -328,6 +328,8 @@ extern tree gettags				PARAMS ((void));
 extern int (*lang_missing_noreturn_ok_p)	PARAMS ((tree));
 
 extern int yyparse				PARAMS ((void));
+extern void free_parser_stacks			PARAMS ((void));
+
 extern stmt_tree current_stmt_tree              PARAMS ((void));
 extern tree *current_scope_stmt_stack           PARAMS ((void));
 extern void begin_stmt_tree                     PARAMS ((tree *));
diff --git a/gcc/c-lex.c b/gcc/c-lex.c
index 30ef877f0b9..acdcf340c32 100644
--- a/gcc/c-lex.c
+++ b/gcc/c-lex.c
@@ -159,6 +159,7 @@ c_common_parse_file (set_yydebug)
   cpp_finish_options (parse_in);
 
   yyparse ();
+  free_parser_stacks ();
 }
 
 struct c_fileinfo *
diff --git a/gcc/c-parse.in b/gcc/c-parse.in
index ff279a10079..679d42d0089 100644
--- a/gcc/c-parse.in
+++ b/gcc/c-parse.in
@@ -61,6 +61,49 @@ end ifobjc
 
 /* Like YYERROR but do call yyerror.  */
 #define YYERROR1 { yyerror ("syntax error"); YYERROR; }
+
+/* Like the default stack expander, except (1) use realloc when possible,
+   (2) impose no hard maxiumum on stack size, (3) REALLY do not use alloca.
+
+   Irritatingly, YYSTYPE is defined after this %{ %} block, so we cannot
+   give malloced_yyvs its proper type.  This is ok since all we need from
+   it is to be able to free it.  */
+
+static short *malloced_yyss;
+static void *malloced_yyvs;
+
+#define yyoverflow(MSG, SS, SSSIZE, VS, VSSIZE, YYSSZ)			\
+do {									\
+  size_t newsize;							\
+  short *newss;								\
+  YYSTYPE *newvs;							\
+  newsize = *(YYSSZ) *= 2;						\
+  if (malloced_yyss)							\
+    {									\
+      newss = (short *)							\
+	really_call_realloc (*(SS), newsize * sizeof (short));		\
+      newvs = (YYSTYPE *)						\
+	really_call_realloc (*(VS), newsize * sizeof (YYSTYPE));	\
+    }									\
+  else									\
+    {									\
+      newss = (short *) really_call_malloc (newsize * sizeof (short));	\
+      newvs = (YYSTYPE *) really_call_malloc (newsize * sizeof (YYSTYPE)); \
+      if (newss)							\
+        memcpy (newss, *(SS), (SSSIZE));				\
+      if (newvs)							\
+        memcpy (newvs, *(VS), (VSSIZE));				\
+    }									\
+  if (!newss || !newvs)							\
+    {									\
+      yyerror (MSG);							\
+      return 2;								\
+    }									\
+  *(SS) = newss;							\
+  *(VS) = newvs;							\
+  malloced_yyss = newss;						\
+  malloced_yyvs = (void *) newvs;					\
+} while (0)
 %}
 
 %start program
@@ -3908,3 +3951,15 @@ make_pointer_declarator (type_quals_attrs, target)
     itarget = tree_cons (attrs, target, NULL_TREE);
   return build1 (INDIRECT_REF, quals, itarget);
 }
+
+/* Free malloced parser stacks if necessary.  */
+
+void
+free_parser_stacks ()
+{
+  if (malloced_yyss)
+    {
+      free (malloced_yyss);
+      free (malloced_yyvs);
+    }
+}
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 4e9ef3ce8ad..237d66964cd 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2002-04-26  Richard Henderson  <rth@redhat.com>
+
+	* parse.y (malloced_yyss, malloced_yyvs): New.
+	(yyoverflow): Re-add.  Set them.
+	(free_parser_stacks): New.
+
 2002-04-26  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/6497
diff --git a/gcc/cp/parse.y b/gcc/cp/parse.y
index 0f963619495..2574d1dd061 100644
--- a/gcc/cp/parse.y
+++ b/gcc/cp/parse.y
@@ -48,6 +48,49 @@ extern struct obstack permanent_obstack;
 /* Like YYERROR but do call yyerror.  */
 #define YYERROR1 { yyerror ("syntax error"); YYERROR; }
 
+/* Like the default stack expander, except (1) use realloc when possible,
+   (2) impose no hard maxiumum on stack size, (3) REALLY do not use alloca.
+
+   Irritatingly, YYSTYPE is defined after this %{ %} block, so we cannot
+   give malloced_yyvs its proper type.  This is ok since all we need from
+   it is to be able to free it.  */
+
+static short *malloced_yyss;
+static void *malloced_yyvs;
+
+#define yyoverflow(MSG, SS, SSSIZE, VS, VSSIZE, YYSSZ)			\
+do {									\
+  size_t newsize;							\
+  short *newss;								\
+  YYSTYPE *newvs;							\
+  newsize = *(YYSSZ) *= 2;						\
+  if (malloced_yyss)							\
+    {									\
+      newss = (short *)							\
+	really_call_realloc (*(SS), newsize * sizeof (short));		\
+      newvs = (YYSTYPE *)						\
+	really_call_realloc (*(VS), newsize * sizeof (YYSTYPE));	\
+    }									\
+  else									\
+    {									\
+      newss = (short *) really_call_malloc (newsize * sizeof (short));	\
+      newvs = (YYSTYPE *) really_call_malloc (newsize * sizeof (YYSTYPE)); \
+      if (newss)							\
+        memcpy (newss, *(SS), (SSSIZE));				\
+      if (newvs)							\
+        memcpy (newvs, *(VS), (VSSIZE));				\
+    }									\
+  if (!newss || !newvs)							\
+    {									\
+      yyerror (MSG);							\
+      return 2;								\
+    }									\
+  *(SS) = newss;							\
+  *(VS) = newvs;							\
+  malloced_yyss = newss;						\
+  malloced_yyvs = (void *) newvs;					\
+} while (0)
+
 #define OP0(NODE) (TREE_OPERAND (NODE, 0))
 #define OP1(NODE) (TREE_OPERAND (NODE, 1))
 
@@ -3970,5 +4013,16 @@ debug_yytranslate (value)
 {
   return yytname[YYTRANSLATE (value)];
 }
-
 #endif
+
+/* Free malloced parser stacks if necessary.  */
+
+void
+free_parser_stacks ()
+{
+  if (malloced_yyss)
+    {
+      free (malloced_yyss);
+      free (malloced_yyvs);
+    }
+}