diff --git a/lib/isc/Makefile.in b/lib/isc/Makefile.in
index 6f3d4634f7..e2e38804d9 100644
--- a/lib/isc/Makefile.in
+++ b/lib/isc/Makefile.in
@@ -33,7 +33,8 @@ UNIXOBJS =	@ISC_ISCIPV6_O@ \
 		unix/app.@O@ unix/dir.@O@ unix/entropy.@O@ \
 		unix/errno2result.@O@ unix/file.@O@ unix/fsaccess.@O@ \
 		unix/interfaceiter.@O@ unix/keyboard.@O@ unix/net.@O@ \
-		unix/socket.@O@ unix/time.@O@ unix/stdio.@O@ unix/stdtime.@O@
+		unix/os.@O@ unix/socket.@O@ unix/time.@O@ \
+		unix/stdio.@O@ unix/stdtime.@O@
 
 
 NLSOBJS =	nls/msgcat.@O@
diff --git a/lib/isc/include/isc/Makefile.in b/lib/isc/include/isc/Makefile.in
index a8a50e2b90..3ca0ebee21 100644
--- a/lib/isc/include/isc/Makefile.in
+++ b/lib/isc/include/isc/Makefile.in
@@ -27,7 +27,7 @@ HEADERS =	assertions.h base64.h bitstring.h boolean.h buffer.h \
 		file.h formatcheck.h fsaccess.h heap.h interfaceiter.h \
 		@ISC_IPV6_H@ lang.h lex.h \
 		lfsr.h lib.h list.h log.h magic.h md5.h mem.h msgcat.h \
-		mutexblock.h netaddr.h ondestroy.h platform.h \
+		mutexblock.h netaddr.h ondestroy.h os.h platform.h \
 		print.h quota.h random.h ratelimiter.h region.h \
 		result.h resultclass.h rwlock.h serial.h sha1.h sockaddr.h \
 		socket.h stdio.h string.h symtab.h task.h taskpool.h timer.h \
diff --git a/lib/isc/include/isc/os.h b/lib/isc/include/isc/os.h
new file mode 100644
index 0000000000..ad673c9de9
--- /dev/null
+++ b/lib/isc/include/isc/os.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2000  Internet Software Consortium.
+ * 
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
+ * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
+ * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+ * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+ * SOFTWARE.
+ */
+
+#ifndef ISC_OS_H
+#define ISC_OS_H 1
+
+#include <isc/lang.h>
+
+ISC_LANG_BEGINDECLS
+
+unsigned int
+isc_os_ncpus(void);
+/*
+ * Return the number of CPUs available on the system, or 1 if this cannot
+ * be determined.
+ */
+
+ISC_LANG_ENDDECLS
+
+#endif /* ISC_OS_H */
diff --git a/lib/isc/unix/Makefile.in b/lib/isc/unix/Makefile.in
index dc980f705c..e8ff723857 100644
--- a/lib/isc/unix/Makefile.in
+++ b/lib/isc/unix/Makefile.in
@@ -30,13 +30,13 @@ CWARNINGS =
 OBJS =		@ISC_IPV6_O@ \
 		app.@O@ dir.@O@ entropy.@O@ errno2result.@O@ file.@O@ \
 		fsaccess.@O@ interfaceiter.@O@ keyboard.@O@ net.@O@ \
-		socket.@O@ stdio.@O@ stdtime.@O@ time.@O@
+		os.@O@ socket.@O@ stdio.@O@ stdtime.@O@ time.@O@
 
 # Alphabetically
 SRCS =		@ISC_IPV6_C@ \
 		app.c dir.c entropy.c errno2result.c file.c \
 		fsaccess.c interfaceiter.c keyboard.c net.c \
-		socket.c stdio.c stdtime.c time.c
+		os.c socket.c stdio.c stdtime.c time.c
 
 SUBDIRS =	include
 TARGETS =	${OBJS}
diff --git a/lib/isc/unix/os.c b/lib/isc/unix/os.c
new file mode 100644
index 0000000000..f9095e7ad2
--- /dev/null
+++ b/lib/isc/unix/os.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2000  Internet Software Consortium.
+ * 
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
+ * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
+ * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+ * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+ * SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <unistd.h>
+
+#include <isc/os.h>
+
+unsigned int
+isc_os_ncpus(void) {
+#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
+	long ncpus;
+
+	ncpus = sysconf(_SC_NPROCESSORS_ONLN);
+	if (ncpus <= 0)
+		return (1);
+#else
+	return (1);
+#endif
+}