diff --git a/libgomp/config/gcn/bar.c b/libgomp/config/gcn/bar.c
index 02fd19710d43..a21529a624b6 100644
--- a/libgomp/config/gcn/bar.c
+++ b/libgomp/config/gcn/bar.c
@@ -43,7 +43,8 @@ gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
       __atomic_store_n (&bar->generation, bar->generation + BAR_INCR,
 			MEMMODEL_RELAXED);
     }
-  asm ("s_barrier" ::: "memory");
+  if (bar->total > 1)
+    asm ("s_barrier" ::: "memory");
 }
 
 void
@@ -71,7 +72,8 @@ gomp_barrier_wait_last (gomp_barrier_t *bar)
 void
 gomp_team_barrier_wake (gomp_barrier_t *bar, int count)
 {
-  asm ("s_barrier" ::: "memory");
+  if (bar->total > 1)
+    asm ("s_barrier" ::: "memory");
 }
 
 void
@@ -97,7 +99,8 @@ gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
 	  state &= ~BAR_CANCELLED;
 	  state += BAR_INCR - BAR_WAS_LAST;
 	  __atomic_store_n (&bar->generation, state, MEMMODEL_RELAXED);
-	  asm ("s_barrier" ::: "memory");
+	  if (bar->total > 1)
+	    asm ("s_barrier" ::: "memory");
 	  return;
 	}
     }
@@ -172,7 +175,8 @@ gomp_team_barrier_wait_cancel_end (gomp_barrier_t *bar,
 	{
 	  state += BAR_INCR - BAR_WAS_LAST;
 	  __atomic_store_n (&bar->generation, state, MEMMODEL_RELAXED);
-	  asm ("s_barrier" ::: "memory");
+	  if (bar->total > 1)
+	    asm ("s_barrier" ::: "memory");
 	  return false;
 	}
     }
@@ -195,7 +199,8 @@ gomp_team_barrier_wait_cancel_end (gomp_barrier_t *bar,
 	  abort();
 	}
 
-      asm ("s_barrier" ::: "memory");
+      if (bar->total > 1)
+	asm ("s_barrier" ::: "memory");
       gen = __atomic_load_n (&bar->generation, MEMMODEL_RELAXED);
       if (__builtin_expect (gen & BAR_CANCELLED, 0))
 	return true;
diff --git a/libgomp/config/nvptx/bar.c b/libgomp/config/nvptx/bar.c
index 125ca3e49ecf..1116561d9315 100644
--- a/libgomp/config/nvptx/bar.c
+++ b/libgomp/config/nvptx/bar.c
@@ -41,7 +41,8 @@ gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
       __atomic_store_n (&bar->generation, bar->generation + BAR_INCR,
 			MEMMODEL_RELEASE);
     }
-  asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
+  if (bar->total > 1)
+    asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
 }
 
 void
@@ -69,7 +70,8 @@ gomp_barrier_wait_last (gomp_barrier_t *bar)
 void
 gomp_team_barrier_wake (gomp_barrier_t *bar, int count)
 {
-  asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
+  if (bar->total > 1)
+    asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
 }
 
 void
@@ -95,7 +97,8 @@ gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
 	  state &= ~BAR_CANCELLED;
 	  state += BAR_INCR - BAR_WAS_LAST;
 	  __atomic_store_n (&bar->generation, state, MEMMODEL_RELEASE);
-	  asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
+	  if (bar->total > 1)
+	    asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
 	  return;
 	}
     }
@@ -104,7 +107,8 @@ gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
   state &= ~BAR_CANCELLED;
   do
     {
-      asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
+      if (bar->total > 1)
+	asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
       gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
       if (__builtin_expect (gen & BAR_TASK_PENDING, 0))
 	{
@@ -158,7 +162,8 @@ gomp_team_barrier_wait_cancel_end (gomp_barrier_t *bar,
 	{
 	  state += BAR_INCR - BAR_WAS_LAST;
 	  __atomic_store_n (&bar->generation, state, MEMMODEL_RELEASE);
-	  asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
+	  if (bar->total > 1)
+	    asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
 	  return false;
 	}
     }
@@ -169,7 +174,8 @@ gomp_team_barrier_wait_cancel_end (gomp_barrier_t *bar,
   generation = state;
   do
     {
-      asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
+      if (bar->total > 1)
+	asm ("bar.sync 1, %0;" : : "r" (32 * bar->total));
       gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
       if (__builtin_expect (gen & BAR_CANCELLED, 0))
 	return true;
diff --git a/libgomp/testsuite/libgomp.c-c++-common/nested-parallel-unbalanced.c b/libgomp/testsuite/libgomp.c-c++-common/nested-parallel-unbalanced.c
new file mode 100644
index 000000000000..e777271dde1d
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/nested-parallel-unbalanced.c
@@ -0,0 +1,31 @@
+/* Ensure that nested parallel regions work even when the number of loop
+   iterations is not divisible by the number of threads.  */
+
+#include <stdlib.h>
+
+int main() {
+  int A[30][40], B[30][40];
+  size_t n = 30;
+
+  for (size_t i = 0; i < 30; ++i)
+    for (size_t j = 0; j < 40; ++j)
+    A[i][j] = 42;
+
+#pragma omp target map(A[0:30][0:40], B[0:30][0:40])
+  {
+#pragma omp parallel for num_threads(8)
+    for (size_t i = 0; i < n; ++i)
+      {
+#pragma omp parallel for
+	for (size_t j = 0; j < n; ++j)
+	  {
+	    B[i][j] = A[i][j];
+	  }
+      }
+  }
+
+for (size_t i = 0; i < n; ++i)
+  for (size_t j = 0; j < n; ++j)
+    if (B[i][j] != 42)
+      abort ();
+}