diff --git a/src/bin/pgbench/.gitignore b/src/bin/pgbench/.gitignore
index aae819e..983a3cd 100644
--- a/src/bin/pgbench/.gitignore
+++ b/src/bin/pgbench/.gitignore
@@ -1,3 +1,4 @@
 /exprparse.c
 /exprscan.c
 /pgbench
+/tmp_check/
diff --git a/src/bin/pgbench/Makefile b/src/bin/pgbench/Makefile
index 18fdf58..e9b1b74 100644
--- a/src/bin/pgbench/Makefile
+++ b/src/bin/pgbench/Makefile
@@ -40,3 +40,9 @@ clean distclean:
 
 maintainer-clean: distclean
 	rm -f exprparse.c exprscan.c
+
+check:
+	$(prove_check)
+
+installcheck:
+	$(prove_installcheck)
diff --git a/src/bin/pgbench/t/001_pgbench.pl b/src/bin/pgbench/t/001_pgbench.pl
new file mode 100644
index 0000000..88e83ab
--- /dev/null
+++ b/src/bin/pgbench/t/001_pgbench.pl
@@ -0,0 +1,25 @@
+use strict;
+use warnings;
+
+use PostgresNode;
+use TestLib;
+use Test::More tests => 3;
+
+# Test concurrent insertion into table with UNIQUE oid column.  DDL expects
+# GetNewOidWithIndex() to successfully avoid violating uniqueness for indexes
+# like pg_class_oid_index and pg_proc_oid_index.  This indirectly exercises
+# LWLock and spinlock concurrency.  This test makes a 5-MiB table.
+my $node = get_new_node('main');
+$node->init;
+$node->start;
+$node->psql('postgres',
+	    'CREATE UNLOGGED TABLE oid_tbl () WITH OIDS; '
+	  . 'ALTER TABLE oid_tbl ADD UNIQUE (oid);');
+my $script = $node->basedir . '/pgbench_script';
+append_to_file($script,
+	'INSERT INTO oid_tbl SELECT FROM generate_series(1,1000);');
+$node->command_like(
+	[   qw(pgbench --no-vacuum --client=5 --protocol=prepared
+		  --transactions=25 --file), $script ],
+	qr{processed: 125/125},
+	'concurrent OID generation');
diff --git a/src/include/port/atomics/generic-xlc.h b/src/include/port/atomics/generic-xlc.h
index 1e8a11e..f24e3af 100644
--- a/src/include/port/atomics/generic-xlc.h
+++ b/src/include/port/atomics/generic-xlc.h
@@ -41,18 +41,22 @@ pg_atomic_compare_exchange_u32_impl(volatile pg_atomic_uint32 *ptr,
 									uint32 *expected, uint32 newval)
 {
 	/*
+	 * XXX: __compare_and_swap is defined to take signed parameters, but that
+	 * shouldn't matter since we don't perform any arithmetic operations.
+	 */
+	bool		ret = __compare_and_swap((volatile int*)&ptr->value,
+										 (int *)expected, (int)newval);
+
+	/*
 	 * xlc's documentation tells us:
 	 * "If __compare_and_swap is used as a locking primitive, insert a call to
 	 * the __isync built-in function at the start of any critical sections."
+	 *
+	 * The critical section begins immediately after __compare_and_swap().
 	 */
 	__isync();
 
-	/*
-	 * XXX: __compare_and_swap is defined to take signed parameters, but that
-	 * shouldn't matter since we don't perform any arithmetic operations.
-	 */
-	return __compare_and_swap((volatile int*)&ptr->value,
-							  (int *)expected, (int)newval);
+	return ret;
 }
 
 #define PG_HAVE_ATOMIC_FETCH_ADD_U32
@@ -69,10 +73,12 @@ static inline bool
 pg_atomic_compare_exchange_u64_impl(volatile pg_atomic_uint64 *ptr,
 									uint64 *expected, uint64 newval)
 {
+	bool		ret = __compare_and_swaplp((volatile long*)&ptr->value,
+										   (long *)expected, (long)newval);
+
 	__isync();
 
-	return __compare_and_swaplp((volatile long*)&ptr->value,
-								(long *)expected, (long)newval);;
+	return ret;
 }
 
 #define PG_HAVE_ATOMIC_FETCH_ADD_U64
diff --git a/src/tools/msvc/clean.bat b/src/tools/msvc/clean.bat
index feb0fe5..d21692f 100755
--- a/src/tools/msvc/clean.bat
+++ b/src/tools/msvc/clean.bat
@@ -94,6 +94,7 @@ if exist src\bin\pg_basebackup\tmp_check rd /s /q src\bin\pg_basebackup\tmp_chec
 if exist src\bin\pg_config\tmp_check rd /s /q src\bin\pg_config\tmp_check
 if exist src\bin\pg_ctl\tmp_check rd /s /q src\bin\pg_ctl\tmp_check
 if exist src\bin\pg_rewind\tmp_check rd /s /q src\bin\pg_rewind\tmp_check
+if exist src\bin\pgbench\tmp_check rd /s /q src\bin\pgbench\tmp_check
 if exist src\bin\scripts\tmp_check rd /s /q src\bin\scripts\tmp_check
 
 REM Clean up datafiles built with contrib