diff --git a/ChangeLog b/ChangeLog
index df8cd6f8f13..5d0b6b1e234 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2014-10-24  Hans-Peter Nilsson  <hp@dummer.localdomain>
+
+	* configure.ac (build_configargs): Don't share config.cache between
+	build subdirs.
+
 2014-10-24  Daniel Hellstrom  <daniel@gaisler.com>
 
 	* config.gcc (sparc*-*-*): Accept mcpu=leon3v7 processor.
diff --git a/configure b/configure
index ce984b1f528..a8f1b8cec58 100755
--- a/configure
+++ b/configure
@@ -7386,8 +7386,10 @@ tbaseargs="$tbaseargs --disable-option-checking"
 
 # For the build-side libraries, we just need to pretend we're native,
 # and not use the same cache file.  Multilibs are neither needed nor
-# desired.
-build_configargs="$build_configargs --cache-file=../config.cache ${baseargs}"
+# desired.  We can't even use the same cache file for all build-side
+# libraries, as they're compiled differently; some with C, some with
+# C++ or with different feature-enabling options.
+build_configargs="$build_configargs --cache-file=./config.cache ${baseargs}"
 
 # For host modules, accept cache file option, or specification as blank.
 case "${cache_file}" in
diff --git a/configure.ac b/configure.ac
index abfd038fa0b..573109277ae 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2922,8 +2922,10 @@ AC_ARG_VAR([target_configargs],
 
 # For the build-side libraries, we just need to pretend we're native,
 # and not use the same cache file.  Multilibs are neither needed nor
-# desired.
-build_configargs="$build_configargs --cache-file=../config.cache ${baseargs}"
+# desired.  We can't even use the same cache file for all build-side
+# libraries, as they're compiled differently; some with C, some with
+# C++ or with different feature-enabling options.
+build_configargs="$build_configargs --cache-file=./config.cache ${baseargs}"
 
 # For host modules, accept cache file option, or specification as blank.
 case "${cache_file}" in