diff --git libgomp/testsuite/libgomp.oacc-c++/c++.exp libgomp/testsuite/libgomp.oacc-c++/c++.exp
index 88b0269..bbdbe2f 100644
--- libgomp/testsuite/libgomp.oacc-c++/c++.exp
+++ libgomp/testsuite/libgomp.oacc-c++/c++.exp
@@ -2,6 +2,7 @@
 
 load_lib libgomp-dg.exp
 load_gcc_lib gcc-dg.exp
+load_gcc_lib torture-options.exp
 
 global shlib_ext
 
@@ -13,13 +14,9 @@ if [info exists lang_include_flags] then {
     unset lang_include_flags
 }
 
-# If a testcase doesn't have special options, use these.
-if ![info exists DEFAULT_CFLAGS] then {
-    set DEFAULT_CFLAGS "-O2"
-}
-
 # Initialize dg.
 dg-init
+torture-init
 
 # Turn on OpenACC.
 lappend ALWAYS_CFLAGS "additional_flags=-fopenacc"
@@ -104,7 +101,26 @@ if { $lang_test_file_found } {
 
 	setenv ACC_DEVICE_TYPE $offload_target_openacc
 
-	dg-runtest $tests "$tagopt" "$libstdcxx_includes $DEFAULT_CFLAGS"
+	# To get better test coverage for device-specific code that is only
+	# ever used in offloading configurations, we'd like more thorough
+	# testing for test cases that deal with offloading, which most of all
+	# OpenACC test cases are.  We enable torture testing, but limit it to
+	# -O0 and -O2 only, to avoid testing times exploding too much, under
+	# the assumption that between -O0 and -O[something] there is the
+	# biggest difference in the overall structure of the generated code.
+	switch $offload_target_openacc {
+	    host {
+		set-torture-options [list \
+					 { -O2 } ]
+	    }
+	    default {
+		set-torture-options [list \
+					 { -O0 } \
+					 { -O2 } ]
+	    }
+	}
+
+	gcc-dg-runtest $tests "$tagopt" "$libstdcxx_includes"
     }
 }
 
@@ -112,4 +128,5 @@ if { $lang_test_file_found } {
 set GCC_UNDER_TEST "$SAVE_GCC_UNDER_TEST"
 
 # All done.
+torture-finish
 dg-finish
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device-2.c libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device-2.c
index e5d9c36..bfcb67d 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device-2.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device-2.c
@@ -1,9 +1,8 @@
-/* { dg-additional-options "-O0" } */
+/* Test the acc_on_device library function. */
+/* { dg-additional-options "-fno-builtin-acc_on_device" } */
 
 #include <openacc.h>
 
-/* acc_on_device might not be folded at -O0, but it should work. */
-
 int main ()
 {
   int dev;
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device.c libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device.c
index 88c000e..e0d8710 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/acc-on-device.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
-/* { dg-additional-options "-O2" } */
+/* We don't expect this to work with optimizations disabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <openacc.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-2.c libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-2.c
index 0f323c8..e8d65df 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-2.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-2.c
@@ -1,4 +1,4 @@
-/* { dg-additional-options "-O2 -fipa-pta" } */
+/* { dg-additional-options "-fipa-pta" } */
 
 #include <stdlib.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-3.c libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-3.c
index 654e750..dd8ca87 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-3.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta-3.c
@@ -1,4 +1,4 @@
-/* { dg-additional-options "-O2 -fipa-pta" } */
+/* { dg-additional-options "-fipa-pta" } */
 
 #include <stdlib.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta.c libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta.c
index 44d4fd2..50e7dc1 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-alias-ipa-pta.c
@@ -1,4 +1,4 @@
-/* { dg-additional-options "-O2 -fipa-pta" } */
+/* { dg-additional-options "-fipa-pta" } */
 
 #include <stdlib.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c
index 4922c9c..e44d26e 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-auto-1.c
@@ -1,5 +1,7 @@
 /* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 #include <openacc.h>
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-dim-default.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-dim-default.c
index 36b882f..80e4363 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-dim-default.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-dim-default.c
@@ -1,5 +1,7 @@
-
-/* { dg-additional-options "-O2 -fopenacc-dim=16:16" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
+/* { dg-additional-options "-fopenacc-dim=16:16" } */
 
 #include <openacc.h>
 #include <alloca.h>
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-1.c
index 23c2a75..0c8e9ff 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-2.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-2.c
index 1a93db3..2316ce3 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-2.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-g-2.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-gwv-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-gwv-1.c
index 26b2df9..e05573f 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-gwv-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-gwv-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-g-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-g-1.c
index c14bddd..17a27b1 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-g-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-g-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-gwv-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-gwv-1.c
index 3de8b09..4566568 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-gwv-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-gwv-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-1.c
index bae5c66..94c752f 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-2.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-2.c
index ada92e3..3c8b4b8 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-2.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-v-2.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-1.c
index 706d0d8..7616b19 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-2.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-2.c
index a073ac8..5f0a439 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-2.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-red-w-2.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-v-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-v-1.c
index b9ec95b..cdba658 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-v-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-v-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-w-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-w-1.c
index 539e41d..a65d535 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-w-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-w-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/loop-wv-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/loop-wv-1.c
index fcb9079..df1a9fc 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/loop-wv-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/loop-wv-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/routine-g-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/routine-g-1.c
index 201dc72..b30424f 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/routine-g-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/routine-g-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/routine-gwv-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/routine-gwv-1.c
index 8fc4cb5..b1cdfd0 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/routine-gwv-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/routine-gwv-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/routine-v-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/routine-v-1.c
index fefeb93..c49f643 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/routine-v-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/routine-v-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/routine-w-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/routine-w-1.c
index 01d1dc8..5806cb3 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/routine-w-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/routine-w-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-1.c
index bd9f1df..49761ce 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-1.c
@@ -1,5 +1,6 @@
-/* { dg-do run } */
-/* { dg-additional-options "-O2" } */
+/* Dead code elimination for blocks guarded by acc_on_device () only works with
+   optimizations enabled.
+   { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
 
 #include <stdio.h>
 
diff --git libgomp/testsuite/libgomp.oacc-c/c.exp libgomp/testsuite/libgomp.oacc-c/c.exp
index 5020e6a..b509a10 100644
--- libgomp/testsuite/libgomp.oacc-c/c.exp
+++ libgomp/testsuite/libgomp.oacc-c/c.exp
@@ -13,14 +13,11 @@ if [info exists lang_include_flags] then {
 
 load_lib libgomp-dg.exp
 load_gcc_lib gcc-dg.exp
-
-# If a testcase doesn't have special options, use these.
-if ![info exists DEFAULT_CFLAGS] then {
-    set DEFAULT_CFLAGS "-O2"
-}
+load_gcc_lib torture-options.exp
 
 # Initialize dg.
 dg-init
+torture-init
 
 # Turn on OpenACC.
 lappend ALWAYS_CFLAGS "additional_flags=-fopenacc"
@@ -67,8 +64,28 @@ foreach offload_target_openacc $offload_targets_s_openacc {
 
     setenv ACC_DEVICE_TYPE $offload_target_openacc
 
-    dg-runtest $tests "$tagopt" $DEFAULT_CFLAGS
+    # To get better test coverage for device-specific code that is only
+    # ever used in offloading configurations, we'd like more thorough
+    # testing for test cases that deal with offloading, which most of all
+    # OpenACC test cases are.  We enable torture testing, but limit it to
+    # -O0 and -O2 only, to avoid testing times exploding too much, under
+    # the assumption that between -O0 and -O[something] there is the
+    # biggest difference in the overall structure of the generated code.
+    switch $offload_target_openacc {
+	host {
+	    set-torture-options [list \
+				     { -O2 } ]
+	}
+	default {
+	    set-torture-options [list \
+				     { -O0 } \
+				     { -O2 } ]
+	}
+    }
+
+    gcc-dg-runtest $tests "$tagopt" ""
 }
 
 # All done.
+torture-finish
 dg-finish
