diff --git a/Makefile.in b/Makefile.in
index b5ce96ef2be..723d210c281 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -346,19 +346,22 @@ else
 CFG_VALGRIND_COMPILE$(1) = $$(CFG_VALGRIND_COMPILE)
 endif
 
+# Add RUSTFLAGS_STAGEN values to the build command
+EXTRAFLAGS_STAGE$(1) = $$(RUSTFLAGS_STAGE$(1))
+
 STAGE$(1)_T_$(2)_H_$(3) := 						\
 	$$(Q)$$(call CFG_RUN_TARG,$(1),				\
 		$$(CFG_VALGRIND_COMPILE$(1)) 			\
 		$$(HBIN$(1)_H_$(3))/rustc$$(X)			\
 		--cfg stage$(1)					\
-		$$(CFG_RUSTC_FLAGS) --target=$(2))
+		$$(CFG_RUSTC_FLAGS) $$(EXTRAFLAGS_STAGE$(1)) --target=$(2))
 
 PERF_STAGE$(1)_T_$(2)_H_$(3) := 				\
 	$$(Q)$$(call CFG_RUN_TARG,$(1),				\
 		$$(CFG_PERF_TOOL) 						\
 		$$(HBIN$(1)_H_$(3))/rustc$$(X)			\
 		--cfg stage$(1)					\
-		$$(CFG_RUSTC_FLAGS) --target=$(2))
+		$$(CFG_RUSTC_FLAGS) $$(EXTRAFLAGS_STAGE$(1)) --target=$(2))
 
 endef