override CPPFLAGS := -DDLSUFFIX=\"$(DLSUFFIX)\" -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
 LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
-ifdef NO_TEMP_INSTALL
-       tbindir=$(abs_top_builddir)/tmp_install/$(bindir)
-       tlibdir=$(abs_top_builddir)/tmp_install/$(libdir)
-       DOINST =
-else
-       tbindir=$(bindir)
-       tlibdir=$(libdir)
-       DOINST = --install
-endif
-
 all: pg_upgrade
 
 pg_upgrade: $(OBJS) | submake-libpq submake-libpgport submake-libpgfeutils
               pg_upgrade_dump_globals.sql \
               pg_upgrade_dump_*.custom pg_upgrade_*.log
 
-check: test.sh all
-       MAKE=$(MAKE) bindir="$(tbindir)" libdir="$(tlibdir)" EXTRA_REGRESS_OPTS="$(EXTRA_REGRESS_OPTS)" $(SHELL) $< $(DOINST)
+check: test.sh all temp-install
+       MAKE=$(MAKE) $(with_temp_install) bindir=$(abs_top_builddir)/tmp_install/$(bindir) EXTRA_REGRESS_OPTS="$(EXTRA_REGRESS_OPTS)" $(SHELL) $<
 
 # installcheck is not supported because there's no meaningful way to test
 # pg_upgrade against a single already-running server
 
 # don't rely on $PWD here, as old shells don't set it
 temp_root=`pwd`/tmp_check
 
-if [ "$1" = '--install' ]; then
-       temp_install=$temp_root/install
-       bindir=$temp_install/$bindir
-       libdir=$temp_install/$libdir
-
-       "$MAKE" -s -C ../.. install DESTDIR="$temp_install"
-
-       # platform-specific magic to find the shared libraries; see pg_regress.c
-       LD_LIBRARY_PATH=$libdir:$LD_LIBRARY_PATH
-       export LD_LIBRARY_PATH
-       DYLD_LIBRARY_PATH=$libdir:$DYLD_LIBRARY_PATH
-       export DYLD_LIBRARY_PATH
-       LIBPATH=$libdir:$LIBPATH
-       export LIBPATH
-       SHLIB_PATH=$libdir:$SHLIB_PATH
-       export SHLIB_PATH
-       PATH=$libdir:$PATH
-
-       # We need to make it use psql from our temporary installation,
-       # because otherwise the installcheck run below would try to
-       # use psql from the proper installation directory, which might
-       # be outdated or missing. But don't override anything else that's
-       # already in EXTRA_REGRESS_OPTS.
-       EXTRA_REGRESS_OPTS="$EXTRA_REGRESS_OPTS --bindir='$bindir'"
-       export EXTRA_REGRESS_OPTS
-fi
-
 : ${oldbindir=$bindir}
 
 : ${oldsrc=../../..}
 oldsrc=`cd "$oldsrc" && pwd`
 newsrc=`cd ../../.. && pwd`
 
+# While in normal cases this will already be set up, adding bindir to
+# path allows test.sh to be invoked with different versions as
+# described in ./TESTING
 PATH=$bindir:$PATH
 export PATH