diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b30c8f8539a..202e59c4ac8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -2,7 +2,13 @@
 
 	Backported from mainline
 	2017-05-22  Jakub Jelinek  <jakub@redhat.com>
- 
+
+	PR middle-end/80809
+	* omp-low.c (finish_taskreg_remap): New function.
+	(finish_taskreg_scan): If unit size of ctx->record_type
+	is non-constant, unshare the size expression and replace
+	decls in it with possible outer var refs.
+
 	PR middle-end/80809
 	* gimplify.c (omp_add_variable): For GOVD_DEBUG_PRIVATE use
 	GOVD_SHARED rather than GOVD_PRIVATE with it.
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 26e6586a070..968075c3df5 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -1913,6 +1913,29 @@ scan_omp_task (gimple_stmt_iterator *gsi, omp_context *outer_ctx)
     }
 }
 
+/* Helper function for finish_taskreg_scan, called through walk_tree.
+   If maybe_lookup_decl_in_outer_context returns non-NULL for some
+   tree, replace it in the expression.  */
+
+static tree
+finish_taskreg_remap (tree *tp, int *walk_subtrees, void *data)
+{
+  if (VAR_P (*tp))
+    {
+      omp_context *ctx = (omp_context *) data;
+      tree t = maybe_lookup_decl_in_outer_ctx (*tp, ctx);
+      if (t != *tp)
+	{
+	  if (DECL_HAS_VALUE_EXPR_P (t))
+	    t = unshare_expr (DECL_VALUE_EXPR (t));
+	  *tp = t;
+	}
+      *walk_subtrees = 0;
+    }
+  else if (IS_TYPE_OR_DECL_P (*tp))
+    *walk_subtrees = 0;
+  return NULL_TREE;
+}
 
 /* If any decls have been made addressable during scan_omp,
    adjust their fields if needed, and layout record types
@@ -2033,6 +2056,11 @@ finish_taskreg_scan (omp_context *ctx)
 	layout_type (ctx->srecord_type);
       tree t = fold_convert_loc (loc, long_integer_type_node,
 				 TYPE_SIZE_UNIT (ctx->record_type));
+      if (TREE_CODE (t) != INTEGER_CST)
+	{
+	  t = unshare_expr (t);
+	  walk_tree (&t, finish_taskreg_remap, ctx, NULL);
+	}
       gimple_omp_task_set_arg_size (ctx->stmt, t);
       t = build_int_cst (long_integer_type_node,
 			 TYPE_ALIGN_UNIT (ctx->record_type));
diff --git a/libgomp/ChangeLog b/libgomp/ChangeLog
index 9a2d4e5a43e..b103098ea50 100644
--- a/libgomp/ChangeLog
+++ b/libgomp/ChangeLog
@@ -2,7 +2,11 @@
 
 	Backported from mainline
 	2017-05-22  Jakub Jelinek  <jakub@redhat.com>
- 
+
+	PR middle-end/80809
+	* testsuite/libgomp.c/pr80809-2.c: New test.
+	* testsuite/libgomp.c/pr80809-3.c: New test.
+
 	PR middle-end/80809
 	* testsuite/libgomp.c/pr80809-1.c: New test.
 
diff --git a/libgomp/testsuite/libgomp.c/pr80809-2.c b/libgomp/testsuite/libgomp.c/pr80809-2.c
new file mode 100644
index 00000000000..48af3707794
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/pr80809-2.c
@@ -0,0 +1,35 @@
+/* PR middle-end/80809 */
+/* { dg-do run } */
+
+__attribute__((noinline, noclone)) void
+foo (int x)
+{
+  int i, v[x], w[16];
+  for (i = 0; i < x; i++)
+    v[i] = i;
+  for (i = 0; i < 16; i++)
+    w[i] = 0;
+#pragma omp parallel
+#pragma omp single
+  for (i = 0; i < 16; i++)
+#pragma omp task firstprivate (v)
+    {
+      int j;
+      for (j = 0; j < x; j++)
+	v[j] += i;
+      for (j = 0; j < x; j++)
+	w[i] += v[j];
+    }
+  for (i = 0; i < 16; i++)
+    if (w[i] != (x - 1) * x / 2 + x * i)
+      __builtin_abort ();
+}
+
+int
+main ()
+{
+  foo (4);
+  foo (27);
+  foo (196);
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c/pr80809-3.c b/libgomp/testsuite/libgomp.c/pr80809-3.c
new file mode 100644
index 00000000000..7e0d17983e4
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/pr80809-3.c
@@ -0,0 +1,42 @@
+/* PR middle-end/80809 */
+/* { dg-do run } */
+
+__attribute__((noinline, noclone)) void
+foo (int x)
+{
+  int i, v[x], w[16];
+  for (i = 0; i < x; i++)
+    v[i] = i;
+  for (i = 0; i < 16; i++)
+    w[i] = 0;
+#pragma omp parallel
+#pragma omp single
+  {
+    int z[x];
+    for (i = 0; i < x; i++)
+      z[0] = 0;
+    for (i = 0; i < 16; i++)
+#pragma omp task firstprivate (z) firstprivate (v)
+      {
+	int j;
+	for (j = 0; j < x; j++)
+	  z[j] = i;
+	for (j = 0; j < x; j++)
+	  v[j] += z[j];
+	for (j = 0; j < x; j++)
+	  w[i] += v[j];
+      }
+  }
+  for (i = 0; i < 16; i++)
+    if (w[i] != (x - 1) * x / 2 + x * i)
+      __builtin_abort ();
+}
+
+int
+main ()
+{
+  foo (4);
+  foo (27);
+  foo (196);
+  return 0;
+}