diff --git libgomp/env.c libgomp/env.c
index 6b5e963..1811bf5 100644
--- libgomp/env.c
+++ libgomp/env.c
@@ -1175,7 +1175,11 @@ handle_omp_display_env (unsigned long stacksize, int wait_policy)
 }
 
 
-static void __attribute__((constructor))
+/* TODO.  See testsuite/lib/libgomp.exp:libgomp_init.  */
+#if 0
+static
+#endif
+void __attribute__((constructor))
 initialize_env (void)
 {
   unsigned long thread_limit_var, stacksize;
diff --git libgomp/libgomp.map libgomp/libgomp.map
index 2b2b953..a3e80b4 100644
--- libgomp/libgomp.map
+++ libgomp/libgomp.map
@@ -337,3 +337,9 @@ GOMP_PLUGIN_1.0 {
 	GOMP_PLUGIN_async_unmap_vars;
 	GOMP_PLUGIN_acc_thread;
 };
+
+# TODO.  See testsuite/lib/libgomp.exp:libgomp_init.
+INTERNAL {
+  global:
+	initialize_env;
+};
diff --git libgomp/testsuite/lib/libgomp.exp libgomp/testsuite/lib/libgomp.exp
index 438777f..982d25e 100644
--- libgomp/testsuite/lib/libgomp.exp
+++ libgomp/testsuite/lib/libgomp.exp
@@ -235,6 +235,57 @@ proc libgomp_init { args } {
     if { $offload_additional_options != "" } {
 	lappend ALWAYS_CFLAGS "additional_flags=${offload_additional_options}"
     }
+
+    # TODO.  Evil hack.  DejaGnu doesn't have a mechanism for setting
+    # environment variables on remote boards.  Thus, we have to fake it, using
+    # GCC's constructor attributes to create object files that install the
+    # desired environment variables.
+    set e_list [list \
+		    [list defaults DUMMY=dummy ] \
+		    [list ACC_DEVICE_TYPE-host ACC_DEVICE_TYPE=host ] \
+		    [list ACC_DEVICE_TYPE-host_nonshm ACC_DEVICE_TYPE=host_nonshm ] \
+		    [list ACC_DEVICE_TYPE-nvidia ACC_DEVICE_TYPE=nvidia ] ]
+    foreach e $e_list {
+	set v [lindex $e 0]
+	set s [lindex $e 1]
+	verbose "creating constructor-setenv: $v: $s"
+	set src constructor-setenv-$v.c
+	set obj constructor-setenv-$v.o
+	set f_src [open $src "w"]
+	puts $f_src "static void __attribute__((constructor(1000)))"
+	puts $f_src "init_env(void) {"
+	puts $f_src "  int putenv(char *);"
+	puts $f_src "  putenv(\"$s\");"
+	puts $f_src "}"
+	if { $v == "defaults" } {
+	    # TODO.  We want libgomp to initialize after the putenv calls.
+	    # But: shared libraries' constructors (and thus
+	    # env.c:initialize_env) will be called before the executable's
+	    # (init_env functions created above), so it will already have been
+	    # initialized (and has to be, in case we're not linking in this
+	    # gunk).  Assuming no execution of other libgomp functionality in
+	    # between (which we're not doing during initialization),
+	    # initialize_env's effects are idempotent when calling it again, so
+	    # we'll do that now, after the putenv calls have been executed.
+	    puts $f_src "static void __attribute__((constructor(1001)))"
+	    puts $f_src "init_libgomp(void) {"
+	    # Some test cases specify -fno-openmp, so libgomp isn't linked in.
+	    puts $f_src "  void initialize_env(void) __attribute__((weak));"
+	    puts $f_src "  if (initialize_env)"
+	    puts $f_src "    initialize_env();"
+	    puts $f_src "}"
+	}
+	close $f_src
+	# TODO.  Using whichever compiler is currently configured...  At least
+	# switch it into C mode.
+	set lines [libgomp_target_compile $src $obj object "additional_flags=-xc"]
+	# TODO.  Error checking.
+	file delete $src
+    }
+    # When adding constructor-setenv-*.o files, make sure to cancel any -x flag
+    # that may have been set before.
+    lappend ALWAYS_CFLAGS "ldflags=-x none"
+    lappend ALWAYS_CFLAGS "ldflags=constructor-setenv-defaults.o"
 }
 
 #
@@ -246,7 +297,6 @@ proc libgomp_target_compile { source dest type options } {
     global libgomp_compile_options
     global gluefile wrap_flags
     global ALWAYS_CFLAGS
-    global GCC_UNDER_TEST
     global lang_test_file
     global lang_library_path
     global lang_link_flags
@@ -274,7 +324,6 @@ proc libgomp_target_compile { source dest type options } {
 
     lappend options "additional_flags=[libio_include_flags]"
     lappend options "timeout=[timeout_value]"
-    lappend options "compiler=$GCC_UNDER_TEST"
 
     set options [concat $libgomp_compile_options $options]
 
@@ -332,8 +381,7 @@ proc check_effective_target_openacc_nvidia_accel_present { } {
 }
 
 # Return 1 if at least one nvidia board is present, and the nvidia device type
-# is selected by default by means of setting the environment variable
-# ACC_DEVICE_TYPE.
+# is selected by default.
 
 proc check_effective_target_openacc_nvidia_accel_selected { } {
     if { ![check_effective_target_openacc_nvidia_accel_present] } {
diff --git libgomp/testsuite/libgomp.c++/c++.exp libgomp/testsuite/libgomp.c++/c++.exp
index 0454f95..d6d525a 100644
--- libgomp/testsuite/libgomp.c++/c++.exp
+++ libgomp/testsuite/libgomp.c++/c++.exp
@@ -4,6 +4,7 @@ load_gcc_lib gcc-dg.exp
 global shlib_ext
 
 set shlib_ext [get_shlib_extension]
+#TODO
 set lang_link_flags "-lstdc++"
 set lang_test_file_found 0
 set lang_library_path "../libstdc++-v3/src/.libs"
@@ -46,6 +47,13 @@ if { $blddir != "" } {
 }
 
 if { $lang_test_file_found } {
+    if ![info exists GXX_UNDER_TEST] then {
+	# TODO.  See libgomp.oacc-c++/c++.exp.
+	set HAVE_SET_GXX_UNDER_TEST ""
+	set GXX_UNDER_TEST "$GCC_UNDER_TEST"
+    }
+    lappend libgomp_compile_options "compiler=$GXX_UNDER_TEST"
+
     # Gather a list of all tests.
     set tests [lsort [find $srcdir/$subdir *.C]]
 
@@ -68,5 +76,10 @@ if { $lang_test_file_found } {
     dg-runtest $tests "" "$libstdcxx_includes $DEFAULT_CFLAGS"
 }
 
+# TODO.  See above.
+if { [info exists HAVE_SET_GXX_UNDER_TEST] } {
+    unset GXX_UNDER_TEST
+}
+
 # All done.
 dg-finish
diff --git libgomp/testsuite/libgomp.c/c.exp libgomp/testsuite/libgomp.c/c.exp
index 300b921..25f347b 100644
--- libgomp/testsuite/libgomp.c/c.exp
+++ libgomp/testsuite/libgomp.c/c.exp
@@ -23,6 +23,8 @@ dg-init
 # Turn on OpenMP.
 lappend ALWAYS_CFLAGS "additional_flags=-fopenmp"
 
+lappend libgomp_compile_options "compiler=$GCC_UNDER_TEST"
+
 # Gather a list of all tests.
 set tests [lsort [find $srcdir/$subdir *.c]]
 
diff --git libgomp/testsuite/libgomp.fortran/fortran.exp libgomp/testsuite/libgomp.fortran/fortran.exp
index 9e6b643..38ed30a 100644
--- libgomp/testsuite/libgomp.fortran/fortran.exp
+++ libgomp/testsuite/libgomp.fortran/fortran.exp
@@ -44,6 +44,11 @@ if { $blddir != "" } {
 }
 
 if { $lang_test_file_found } {
+    if ![info exists GFORTRAN_UNDER_TEST] then {
+	set GFORTRAN_UNDER_TEST $GCC_UNDER_TEST
+    }
+    lappend libgomp_compile_options "compiler=$GFORTRAN_UNDER_TEST"
+
     # Gather a list of all tests.
     set tests [lsort [find $srcdir/$subdir *.\[fF\]{,90,95,03,08}]]
 
diff --git libgomp/testsuite/libgomp.graphite/graphite.exp libgomp/testsuite/libgomp.graphite/graphite.exp
index d737c85..716cdc3 100644
--- libgomp/testsuite/libgomp.graphite/graphite.exp
+++ libgomp/testsuite/libgomp.graphite/graphite.exp
@@ -48,6 +48,8 @@ dg-init
 # Turn on OpenMP.
 lappend ALWAYS_CFLAGS "additional_flags=-fopenmp"
 
+lappend libgomp_compile_options "compiler=$GCC_UNDER_TEST"
+
 # Gather a list of all tests.
 set tests [lsort [find $srcdir/$subdir *.c]]
 
diff --git libgomp/testsuite/libgomp.oacc-c++/c++.exp libgomp/testsuite/libgomp.oacc-c++/c++.exp
index 3b97024..0272b98 100644
--- libgomp/testsuite/libgomp.oacc-c++/c++.exp
+++ libgomp/testsuite/libgomp.oacc-c++/c++.exp
@@ -6,6 +6,7 @@ load_gcc_lib gcc-dg.exp
 global shlib_ext
 
 set shlib_ext [get_shlib_extension]
+#TODO
 set lang_link_flags "-lstdc++"
 set lang_test_file_found 0
 set lang_library_path "../libstdc++-v3/src/.libs"
@@ -24,11 +25,6 @@ dg-init
 # Turn on OpenACC.
 lappend ALWAYS_CFLAGS "additional_flags=-fopenacc"
 
-# Switch into C++ mode.  Otherwise, the libgomp.oacc-c-c++-common/*.c
-# files would be compiled as C files.
-set SAVE_GCC_UNDER_TEST "$GCC_UNDER_TEST"
-set GCC_UNDER_TEST "$GCC_UNDER_TEST -x c++"
-
 set blddir [lookfor_file [get_multilibs] libgomp]
 
 
@@ -53,6 +49,14 @@ if { $blddir != "" } {
 }
 
 if { $lang_test_file_found } {
+    if ![info exists GXX_UNDER_TEST] then {
+	# Use GCC_UNDER_TEST, but switch into C++ mode, as otherwise the
+	# libgomp.oacc-c-c++-common/*.c files would be compiled as C files.
+	set HAVE_SET_GXX_UNDER_TEST ""
+	set GXX_UNDER_TEST "$GCC_UNDER_TEST -x c++"
+    }
+    lappend libgomp_compile_options "compiler=$GXX_UNDER_TEST"
+
     # Gather a list of all tests.
     set tests [lsort [concat \
 			  [find $srcdir/$subdir *.C] \
@@ -74,8 +78,13 @@ if { $lang_test_file_found } {
     }
 
     # Test OpenACC with available accelerators.
+    set SAVE_ALWAYS_CFLAGS "$ALWAYS_CFLAGS"
     foreach offload_target_openacc $offload_targets_s_openacc {
+	set ALWAYS_CFLAGS "$SAVE_ALWAYS_CFLAGS"
 	set tagopt "-DACC_DEVICE_TYPE_$offload_target_openacc=1"
+	# Set $ACC_DEVICE_TYPE.  See the comments in
+	# ../lib/libgomp.exp:libgomp_init.
+	lappend ALWAYS_CFLAGS "ldflags=constructor-setenv-ACC_DEVICE_TYPE-$offload_target_openacc.o"
 
 	switch $offload_target_openacc {
 	    host {
@@ -105,14 +114,14 @@ if { $lang_test_file_found } {
 	}
 	set tagopt "$tagopt -DACC_MEM_SHARED=$acc_mem_shared"
 
-	setenv ACC_DEVICE_TYPE $offload_target_openacc
-
 	dg-runtest $tests "$tagopt" "$libstdcxx_includes $DEFAULT_CFLAGS"
     }
 }
 
 # See above.
-set GCC_UNDER_TEST "$SAVE_GCC_UNDER_TEST"
+if { [info exists HAVE_SET_GXX_UNDER_TEST] } {
+    unset GXX_UNDER_TEST
+}
 
 # All done.
 dg-finish
diff --git libgomp/testsuite/libgomp.oacc-c/c.exp libgomp/testsuite/libgomp.oacc-c/c.exp
index 326b988..03946a6 100644
--- libgomp/testsuite/libgomp.oacc-c/c.exp
+++ libgomp/testsuite/libgomp.oacc-c/c.exp
@@ -25,6 +25,8 @@ dg-init
 # Turn on OpenACC.
 lappend ALWAYS_CFLAGS "additional_flags=-fopenacc"
 
+lappend libgomp_compile_options "compiler=$GCC_UNDER_TEST"
+
 # Gather a list of all tests.
 set tests [lsort [concat \
 		      [find $srcdir/$subdir *.c] \
@@ -39,6 +41,9 @@ set SAVE_ALWAYS_CFLAGS "$ALWAYS_CFLAGS"
 foreach offload_target_openacc $offload_targets_s_openacc {
     set ALWAYS_CFLAGS "$SAVE_ALWAYS_CFLAGS"
     set tagopt "-DACC_DEVICE_TYPE_$offload_target_openacc=1"
+    # Set $ACC_DEVICE_TYPE.  See the comments in
+    # ../lib/libgomp.exp:libgomp_init.
+    lappend ALWAYS_CFLAGS "ldflags=constructor-setenv-ACC_DEVICE_TYPE-$offload_target_openacc.o"
 
     switch $offload_target_openacc {
 	host {
@@ -68,8 +73,6 @@ foreach offload_target_openacc $offload_targets_s_openacc {
     }
     set tagopt "$tagopt -DACC_MEM_SHARED=$acc_mem_shared"
 
-    setenv ACC_DEVICE_TYPE $offload_target_openacc
-
     dg-runtest $tests "$tagopt" $DEFAULT_CFLAGS
 }
 
diff --git libgomp/testsuite/libgomp.oacc-fortran/fortran.exp libgomp/testsuite/libgomp.oacc-fortran/fortran.exp
index a8aaff0..0814426 100644
--- libgomp/testsuite/libgomp.oacc-fortran/fortran.exp
+++ libgomp/testsuite/libgomp.oacc-fortran/fortran.exp
@@ -46,6 +46,11 @@ if { $blddir != "" } {
 }
 
 if { $lang_test_file_found } {
+    if ![info exists GFORTRAN_UNDER_TEST] then {
+	set GFORTRAN_UNDER_TEST $GCC_UNDER_TEST
+    }
+    lappend libgomp_compile_options "compiler=$GFORTRAN_UNDER_TEST"
+
     # Gather a list of all tests.
     set tests [lsort [find $srcdir/$subdir *.\[fF\]{,90,95,03,08}]]
 
@@ -66,8 +71,13 @@ if { $lang_test_file_found } {
     set_ld_library_path_env_vars
 
     # Test OpenACC with available accelerators.
+    set SAVE_ALWAYS_CFLAGS "$ALWAYS_CFLAGS"
     foreach offload_target_openacc $offload_targets_s_openacc {
+	set ALWAYS_CFLAGS "$SAVE_ALWAYS_CFLAGS"
 	set tagopt "-DACC_DEVICE_TYPE_$offload_target_openacc=1"
+	# Set $ACC_DEVICE_TYPE.  See the comments in
+	# ../lib/libgomp.exp:libgomp_init.
+	lappend ALWAYS_CFLAGS "ldflags=constructor-setenv-ACC_DEVICE_TYPE-$offload_target_openacc.o"
 
 	switch $offload_target_openacc {
 	    host {
@@ -91,8 +101,6 @@ if { $lang_test_file_found } {
 	}
 	set tagopt "$tagopt -DACC_MEM_SHARED=$acc_mem_shared"
 
-	setenv ACC_DEVICE_TYPE $offload_target_openacc
-
 	# For Fortran we're doing torture testing, as Fortran has far more tests
 	# with arrays etc. that testing just -O0 or -O2 is insufficient, that is
 	# typically not the case for C/C++.
