diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 074d2db..838ab11 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 ####
 # kbuild: Generic definitions
 
@@ -24,10 +25,18 @@
 basetarget = $(basename $(notdir $@))
 
 ###
+# real prerequisites without phony targets
+real-prereqs = $(filter-out $(PHONY), $^)
+
+###
 # Escape single quote for use in echo statements
 escsq = $(subst $(squote),'\$(squote)',$1)
 
 ###
+# Quote a string to pass it to C files. foo => '"foo"'
+stringify = $(squote)$(quote)$1$(quote)$(squote)
+
+###
 # Easy method for doing a status message
        kecho := :
  quiet_kecho := echo
@@ -62,18 +71,19 @@
 
 ######
 # gcc support functions
-# See documentation in Documentation/kbuild/makefiles.txt
+# See documentation in Documentation/kbuild/makefiles.rst
 
 # cc-cross-prefix
 # Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
-# Return first prefix where a prefix$(CC) is found in PATH.
-# If no $(CC) found in PATH with listed prefixes return nothing
-cc-cross-prefix =  \
-	$(word 1, $(foreach c,$(1),                                   \
-		$(shell set -e;                                       \
-		if (which $(strip $(c))$(CC)) > /dev/null 2>&1 ; then \
-			echo $(c);                                    \
-		fi)))
+# Return first <prefix> where a <prefix>gcc is found in PATH.
+# If no gcc found in PATH with listed prefixes return nothing
+#
+# Note: '2>/dev/null' is here to force Make to invoke a shell. Otherwise, it
+# would try to directly execute the shell builtin 'command'. This workaround
+# should be kept for a long time since this issue was fixed only after the
+# GNU Make 4.2.1 release.
+cc-cross-prefix = $(firstword $(foreach c, $(1), \
+			$(if $(shell command -v -- $(c)gcc 2>/dev/null), $(c))))
 
 # output directory for tests below
 TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
@@ -138,18 +148,13 @@
 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
 # Usage:
 # $(Q)$(MAKE) $(build)=dir
-build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
+build := -f $(srctree)/scripts/Makefile.build obj
 
 ###
-# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=
-# Usage:
-# $(Q)$(MAKE) $(modbuiltin)=dir
-modbuiltin := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.modbuiltin obj
-
-# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=dir
+# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=
 # Usage:
 # $(Q)$(MAKE) $(clean)=dir
-clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj
+clean := -f $(srctree)/scripts/Makefile.clean obj
 
 # Prefix -I with $(srctree) if it is not an absolute path.
 # skip if -I has no parameter
@@ -167,9 +172,6 @@
 # printing commands
 cmd = @set -e; $(echo-cmd) $(cmd_$(1))
 
-# Add $(obj)/ for paths that are not absolute
-objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
-
 ###
 # if_changed      - execute command if any prerequisite is newer than
 #                   target, or command line has changed