diff --git a/fixincludes/ChangeLog b/fixincludes/ChangeLog
index 5b3d9ae1055..3f93053e121 100644
--- a/fixincludes/ChangeLog
+++ b/fixincludes/ChangeLog
@@ -1,3 +1,7 @@
+2020-02-20  Alexandre Oliva <oliva@adacore.com>
+
+	* mkheaders.in: Don't require build-time shell on host.
+
 2020-02-13  Matheus Castanho  <msc@linux.ibm.com>
 
 	* fixinc.in: Skip machine_name fix on powerpc*-*-linux*.
diff --git a/fixincludes/mkheaders.in b/fixincludes/mkheaders.in
index a293a57a73b..4109dc633dd 100644
--- a/fixincludes/mkheaders.in
+++ b/fixincludes/mkheaders.in
@@ -77,11 +77,29 @@ libexecsubdir=${libexecdir}/gcc/${target_noncanonical}/${version}
 itoolsdir=${libexecsubdir}/install-tools
 itoolsdatadir=${libsubdir}/install-tools
 incdir=${libsubdir}/include-fixed
-mkinstalldirs="@SHELL@ ${itoolsdir}/mkinstalldirs"
+mkinstalldirs="${itoolsdir}/mkinstalldirs"
 
 cd ${itoolsdir}
 rm -rf ${incdir}/*
 
+for shell in $CONFIG_SHELL $SHELL @SHELL@ /bin/sh ""; do
+  if { test -x $shell || test -x $shell.exe; } \
+  && $shell $mkinstalldirs > /dev/null 2>&1; then
+    mkinstalldirs="$shell $mkinstalldirs"
+    break
+  elif test x$shell = x; then
+    if $mkinstalldirs > /dev/null 2>&1; then
+      break
+    elif test ! -f $mkinstalldirs; then
+      echo mkheaders: could not find $mkinstalldirs >&2
+      exit 1
+    else
+      echo mkheaders: please rerun with CONFIG_SHELL set to a working Bourne shell >&2
+      exit 1
+    fi
+  fi
+done
+
 for ml in `cat ${itoolsdatadir}/fixinc_list`; do
   sysroot_headers_suffix=`echo ${ml} | sed -e 's/;.*$//'`
   multi_dir=`echo ${ml} | sed -e 's/^[^;]*;//'`
@@ -91,7 +109,7 @@ for ml in `cat ${itoolsdatadir}/fixinc_list`; do
   if [ x${STMP_FIXINC} != x ] ; then
 	TARGET_MACHINE="${target}" target_canonical="${target}" \
 	    MACRO_LIST="${itoolsdatadir}/macro_list" \
-	    @SHELL@ ./fixinc.sh ${subincdir} \
+	    $shell ./fixinc.sh ${subincdir} \
 	    ${isysroot}${SYSTEM_HEADER_DIR} ${OTHER_FIXINCLUDES_DIRS}
 	rm -f ${subincdir}/syslimits.h
 	if [ -f ${subincdir}/limits.h ]; then