diff --git a/arch/ia64/kernel/Makefile b/arch/ia64/kernel/Makefile
index cea91f1..87fea11 100644
--- a/arch/ia64/kernel/Makefile
+++ b/arch/ia64/kernel/Makefile
@@ -73,6 +73,39 @@
 # Note: kbuild does not track this dependency due to usage of .incbin
 $(obj)/gate-data.o: $(obj)/gate.so
 
+# Calculate NR_IRQ = max(IA64_NATIVE_NR_IRQS, XEN_NR_IRQS, ...) based on config
+define sed-y
+	"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
+endef
+quiet_cmd_nr_irqs = GEN     $@
+define cmd_nr_irqs
+	(set -e; \
+	 echo "#ifndef __ASM_NR_IRQS_H__"; \
+	 echo "#define __ASM_NR_IRQS_H__"; \
+	 echo "/*"; \
+	 echo " * DO NOT MODIFY."; \
+	 echo " *"; \
+	 echo " * This file was generated by Kbuild"; \
+	 echo " *"; \
+	 echo " */"; \
+	 echo ""; \
+	 sed -ne $(sed-y) $<; \
+	 echo ""; \
+	 echo "#endif" ) > $@
+endef
+
+# We use internal kbuild rules to avoid the "is up to date" message from make
+arch/$(SRCARCH)/kernel/nr-irqs.s: $(srctree)/arch/$(SRCARCH)/kernel/nr-irqs.c \
+				$(wildcard $(srctree)/include/asm-ia64/*/irq.h)
+	$(Q)mkdir -p $(dir $@)
+	$(call if_changed_dep,cc_s_c)
+
+include/asm-ia64/nr-irqs.h: arch/$(SRCARCH)/kernel/nr-irqs.s
+	$(Q)mkdir -p $(dir $@)
+	$(call cmd,nr_irqs)
+
+clean-files += $(objtree)/include/asm-ia64/nr-irqs.h
+
 #
 # native ivt.S and entry.S
 #