diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
index 815bdf9e0..ef59c7049 100644
--- a/glib/gvariant-core.c
+++ b/glib/gvariant-core.c
@@ -506,6 +506,10 @@ g_variant_alloc (const GVariantType *type,
  *
  * A reference is taken on @bytes.
  *
+ * The data in @bytes must be aligned appropriately for the @type being loaded.
+ * Otherwise this function will internally create a copy of the memory (since
+ * GLib 2.60) or (in older versions) fail and exit the process.
+ *
  * Returns: (transfer none): a new #GVariant with a floating reference
  *
  * Since: 2.36
@@ -518,14 +522,50 @@ g_variant_new_from_bytes (const GVariantType *type,
   GVariant *value;
   guint alignment;
   gsize size;
+  GBytes *owned_bytes = NULL;
 
   value = g_variant_alloc (type, TRUE, trusted);
 
-  value->contents.serialised.bytes = g_bytes_ref (bytes);
-
   g_variant_type_info_query (value->type_info,
                              &alignment, &size);
 
+  /* Ensure the alignment is correct. This is a huge performance hit if it’s
+   * not correct, but that’s better than aborting if a caller provides data
+   * with the wrong alignment (which is likely to happen very occasionally, and
+   * only cause an abort on some architectures — so is unlikely to be caught
+   * in testing). Callers can always actively ensure they use the correct
+   * alignment to avoid the performance hit. */
+  if ((alignment & (gsize) g_bytes_get_data (bytes, NULL)) != 0)
+    {
+#ifdef HAVE_POSIX_MEMALIGN
+      gpointer aligned_data = NULL;
+      gsize aligned_size = g_bytes_get_size (bytes);
+
+      /* posix_memalign() requires the alignment to be a multiple of
+       * sizeof(void*), and a power of 2. See g_variant_type_info_query() for
+       * details on the alignment format. */
+      if (posix_memalign (&aligned_data, MAX (sizeof (void *), alignment + 1),
+                          aligned_size) != 0)
+        g_error ("posix_memalign failed");
+
+      memcpy (aligned_data, g_bytes_get_data (bytes, NULL), aligned_size);
+
+      bytes = owned_bytes = g_bytes_new_with_free_func (aligned_data,
+                                                        aligned_size,
+                                                        free, aligned_data);
+      aligned_data = NULL;
+#else
+      /* NOTE: there may be platforms that lack posix_memalign() and also
+       * have malloc() that returns non-8-aligned.  if so, we need to try
+       * harder here.
+       */
+      bytes = owned_bytes = g_bytes_new (g_bytes_get_data (bytes, NULL),
+                                         g_bytes_get_size (bytes));
+#endif
+    }
+
+  value->contents.serialised.bytes = g_bytes_ref (bytes);
+
   if (size && g_bytes_get_size (bytes) != size)
     {
       /* Creating a fixed-sized GVariant with a bytes of the wrong
@@ -543,6 +583,8 @@ g_variant_new_from_bytes (const GVariantType *type,
       value->contents.serialised.data = g_bytes_get_data (bytes, &value->size);
     }
 
+  g_clear_pointer (&owned_bytes, g_bytes_unref);
+
   return value;
 }
 
diff --git a/glib/gvariant.c b/glib/gvariant.c
index d45b487ad..983d4704c 100644
--- a/glib/gvariant.c
+++ b/glib/gvariant.c
@@ -307,6 +307,11 @@
  * Constructs a new trusted #GVariant instance from the provided data.
  * This is used to implement g_variant_new_* for all the basic types.
  *
+ * Note: @data must be backed by memory that is aligned appropriately for the
+ * @type being loaded. Otherwise this function will internally create a copy of
+ * the memory (since GLib 2.60) or (in older versions) fail and exit the
+ * process.
+ *
  * Returns: a new floating #GVariant
  */
 static GVariant *
@@ -5986,6 +5991,11 @@ g_variant_byteswap (GVariant *value)
  * needed.  The exact time of this call is unspecified and might even be
  * before this function returns.
  *
+ * Note: @data must be backed by memory that is aligned appropriately for the
+ * @type being loaded. Otherwise this function will internally create a copy of
+ * the memory (since GLib 2.60) or (in older versions) fail and exit the
+ * process.
+ *
  * Returns: (transfer none): a new floating #GVariant of type @type
  *
  * Since: 2.24
diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
index 5414da540..827e47532 100644
--- a/glib/tests/gvariant.c
+++ b/glib/tests/gvariant.c
@@ -4965,6 +4965,51 @@ test_normal_checking_empty_object_path (void)
   g_variant_unref (variant);
 }
 
+/* Test that constructing a #GVariant from data which is not correctly aligned
+ * for the variant type is OK, by loading a variant from data at various offsets
+ * which are aligned and unaligned. When unaligned, a slow construction path
+ * should be taken. */
+static void
+test_unaligned_construction (void)
+{
+  const guint8 data[] = {
+    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+    0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
+  };
+  GVariant *variant = NULL;
+  GVariant *normal_variant = NULL;
+  gsize i, offset;
+  const struct {
+    const GVariantType *type;
+    gsize size;
+    gsize max_offset;
+  } vectors[] = {
+    { G_VARIANT_TYPE_UINT64, sizeof (guint64), sizeof (guint64) },
+    { G_VARIANT_TYPE_UINT32, sizeof (guint32), sizeof (guint32) },
+    { G_VARIANT_TYPE_UINT16, sizeof (guint16), sizeof (guint16) },
+    { G_VARIANT_TYPE_BYTE, sizeof (guint8), 3 },
+  };
+
+  G_STATIC_ASSERT (sizeof (guint64) * 2 <= sizeof (data));
+
+  for (i = 0; i < G_N_ELEMENTS (vectors); i++)
+    {
+      for (offset = 0; offset < vectors[i].max_offset; offset++)
+        {
+          variant = g_variant_new_from_data (vectors[i].type, data + offset,
+                                             vectors[i].size,
+                                             FALSE, NULL, NULL);
+          g_assert_nonnull (variant);
+
+          normal_variant = g_variant_get_normal_form (variant);
+          g_assert_nonnull (normal_variant);
+
+          g_variant_unref (normal_variant);
+          g_variant_unref (variant);
+        }
+    }
+}
+
 int
 main (int argc, char **argv)
 {
@@ -5045,5 +5090,8 @@ main (int argc, char **argv)
   g_test_add_func ("/gvariant/recursion-limits/array-in-variant",
                    test_recursion_limits_array_in_variant);
 
+  g_test_add_func ("/gvariant/unaligned-construction",
+                   test_unaligned_construction);
+
   return g_test_run ();
 }