diff --git a/include/ChangeLog b/include/ChangeLog
index a6cf609fe190c8af9c6a2a9fa2d8bb283bebe3ad..273b59c2a18a8e51733c2809de3387290ea44530 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,12 @@
+2009-05-31  Ian Lance Taylor  <iant@google.com>
+
+	* ansidecl.h: Add extern "C" when compiling with C++.  Treat C++
+	the way we treat an ISO C compiler.  Don't define inline as a
+	macdro when compiling with C++.
+	* dyn-string.h: Add header guard DYN_STRING_H.  Add extern "C"
+	when compiling with C++.
+	* fibheap.h: Add extern "C" when compiling with C++.
+
 2009-04-22  Taras Glek <tglek@mozilla.com>
 
 	* hashtab.h: Update GTY annotations to new syntax.
diff --git a/include/ansidecl.h b/include/ansidecl.h
index c19955a98a677f66dc9bf5e54291ac0f3aa3efff..c83b8c039d9982c72604c38a7939d586885ea182 100644
--- a/include/ansidecl.h
+++ b/include/ansidecl.h
@@ -1,5 +1,6 @@
 /* ANSI and traditional C compatability macros
-   Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001
+   Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
+   2002, 2003, 2004, 2005, 2006, 2007, 2009
    Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -114,6 +115,10 @@ Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
 #ifndef	_ANSIDECL_H
 #define _ANSIDECL_H	1
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Every source file includes this file,
    so they will all get the switch for lint.  */
 /* LINTLIBRARY */
@@ -136,7 +141,7 @@ So instead we use the macro below and test it against specific values.  */
 #define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
 #endif /* GCC_VERSION */
 
-#if defined (__STDC__) || defined (_AIX) || (defined (__mips) && defined (_SYSTYPE_SVR4)) || defined(_WIN32) || (defined(__alpha) && defined(__cplusplus))
+#if defined (__STDC__) || defined(__cplusplus) || defined (_AIX) || (defined (__mips) && defined (_SYSTYPE_SVR4)) || defined(_WIN32)
 /* All known AIX compilers implement these things (but don't always
    define __STDC__).  The RISC/OS MIPS compiler defines these things
    in SVR4 mode, but does not define __STDC__.  */
@@ -173,7 +178,7 @@ So instead we use the macro below and test it against specific values.  */
 /* inline requires special treatment; it's in C99, and GCC >=2.7 supports
    it too, but it's not in C89.  */
 #undef inline
-#if __STDC_VERSION__ > 199901L
+#if __STDC_VERSION__ > 199901L || defined(__cplusplus)
 /* it's a keyword */
 #else
 # if GCC_VERSION >= 2007
@@ -390,4 +395,8 @@ So instead we use the macro below and test it against specific values.  */
 #define __extension__
 #endif
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif	/* ansidecl.h	*/
diff --git a/include/dyn-string.h b/include/dyn-string.h
index 44e33deba3a5a05731a94153cb05e10a7614072d..2b147271e5f85b52ac2bc07f6696dbb08fb0e80b 100644
--- a/include/dyn-string.h
+++ b/include/dyn-string.h
@@ -1,5 +1,6 @@
 /* An abstract string datatype.
-   Copyright (C) 1998, 1999, 2000, 2002, 2004 Free Software Foundation, Inc.
+   Copyright (C) 1998, 1999, 2000, 2002, 2004, 2005, 2009
+   Free Software Foundation, Inc.
    Contributed by Mark Mitchell (mark@markmitchell.com).
 
 This file is part of GCC.
@@ -19,6 +20,12 @@ along with GCC; see the file COPYING.  If not, write to
 the Free Software Foundation, 51 Franklin Street - Fifth Floor,
 Boston, MA 02110-1301, USA.  */
 
+#ifndef DYN_STRING_H
+#define DYN_STRING_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 typedef struct dyn_string
 {
@@ -58,3 +65,9 @@ extern int dyn_string_append_cstr (dyn_string_t, const char *);
 extern int dyn_string_append_char (dyn_string_t, int);
 extern int dyn_string_substring (dyn_string_t,  dyn_string_t, int, int);
 extern int dyn_string_eq (dyn_string_t, dyn_string_t);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* !defined (DYN_STRING_H) */
diff --git a/include/fibheap.h b/include/fibheap.h
index 348c4ae2638987404652212f007b63d8be6be364..a3d09dd9db8d70f1e4f9468f95243686f315ea7f 100644
--- a/include/fibheap.h
+++ b/include/fibheap.h
@@ -1,5 +1,6 @@
 /* A Fibonacci heap datatype.
-   Copyright 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
+   Copyright 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2009
+   Free Software Foundation, Inc.
    Contributed by Daniel Berlin (dan@cgsoftware.com).
 
 This file is part of GCC.
@@ -42,6 +43,10 @@ Boston, MA 02110-1301, USA.  */
 
 #include "ansidecl.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef long fibheapkey_t;
 
 typedef struct fibheap
@@ -83,4 +88,8 @@ extern void *fibheap_delete_node (fibheap_t, fibnode_t);
 extern void fibheap_delete (fibheap_t);
 extern fibheap_t fibheap_union (fibheap_t, fibheap_t);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _FIBHEAP_H_ */