Index: uspace/lib/libc/Makefile
===================================================================
--- uspace/lib/libc/Makefile	(revision e4052289128156d1d0315bc11b697d7346ad5cf3)
+++ uspace/lib/libc/Makefile	(revision ed632988c6b2a483a45b26f06f129ef8a5c69e75)
@@ -33,7 +33,7 @@
 all: ../../../Makefile.config ../../../config.h ../../../config.defs
 	-[ -f $(DEPEND) ] && mv -f $(DEPEND) $(DEPEND_PREV)
-	$(MAKE) -f Makefile.build
+	$(MAKE) -f Makefile.build PRECHECK=$(PRECHECK)
 
 clean:
-	rm -f $(DEPEND) $(DEPEND_PREV) $(INCLUDE_KERNEL) $(INCLUDE_ARCH) $(INCLUDE_LIBARCH) $(LIBC) arch/*/_link.ld
+	rm -f $(DEPEND) $(DEPEND_PREV) $(JOB) $(INCLUDE_KERNEL) $(INCLUDE_ARCH) $(INCLUDE_LIBARCH) $(LIBC) arch/*/_link.ld
 	find generic/ arch/*/ -name '*.o' -follow -exec rm \{\} \;
Index: uspace/lib/libc/Makefile.build
===================================================================
--- uspace/lib/libc/Makefile.build	(revision e4052289128156d1d0315bc11b697d7346ad5cf3)
+++ uspace/lib/libc/Makefile.build	(revision ed632988c6b2a483a45b26f06f129ef8a5c69e75)
@@ -112,10 +112,19 @@
 %.o: %.S $(DEPEND)
 	$(CC) $(DEFS) $(AFLAGS) $(CFLAGS) -D__ASM__ -c $< -o $@
+ifeq ($(PRECHECK),y)
+	$(JOBFILE) $(JOB) $< $@ as asm/preproc $(DEFS) $(AFLAGS) $(CFLAGS) -D__ASM__
+endif
 
 %.o: %.s $(DEPEND)
 	$(AS) $(AFLAGS) $< -o $@
+ifeq ($(PRECHECK),y)
+	$(JOBFILE) $(JOB) $< $@ as asm $(AFLAGS)
+endif
 
 %.o: %.c $(DEPEND)
 	$(CC) $(DEFS) $(CFLAGS) -c $< -o $@
+ifeq ($(PRECHECK),y)
+	$(JOBFILE) $(JOB) $< $@ cc core $(DEFS) $(CFLAGS)
+endif
 
 $(DEPEND): $(INCLUDE_KERNEL) $(INCLUDE_ARCH) $(INCLUDE_LIBARCH)
Index: uspace/lib/libc/Makefile.common
===================================================================
--- uspace/lib/libc/Makefile.common	(revision e4052289128156d1d0315bc11b697d7346ad5cf3)
+++ uspace/lib/libc/Makefile.common	(revision ed632988c6b2a483a45b26f06f129ef8a5c69e75)
@@ -33,4 +33,5 @@
 DEPEND = Makefile.depend
 DEPEND_PREV = $(DEPEND).prev
+JOB = libc.job
 LIBC = libc.a
 INCLUDE_KERNEL = include/kernel
Index: uspace/lib/libc/Makefile.toolchain
===================================================================
--- uspace/lib/libc/Makefile.toolchain	(revision e4052289128156d1d0315bc11b697d7346ad5cf3)
+++ uspace/lib/libc/Makefile.toolchain	(revision ed632988c6b2a483a45b26f06f129ef8a5c69e75)
@@ -78,4 +78,6 @@
 #
 
+JOBFILE = $(LIBC_PREFIX)/../../../tools/jobfile.py
+
 ifeq ($(COMPILER),gcc_cross)
 	CC = $(TOOLCHAIN_DIR)/$(TARGET)-gcc