diff --git a/gcc/asan.h b/gcc/asan.h
index 028afdd2e7d16245c6cbbe106b7ccb9c5034d542..c5492ce35980d0b26d4707f96482b69dc76a525a 100644
--- a/gcc/asan.h
+++ b/gcc/asan.h
@@ -31,6 +31,7 @@ extern rtx hwasan_with_tag (rtx, poly_int64);
 extern void hwasan_tag_init ();
 extern rtx hwasan_create_untagged_base (rtx);
 extern void hwasan_emit_prologue (rtx *, rtx *, poly_int64 *, uint8_t *, size_t);
+extern rtx_insn *hwasan_emit_uncolour_frame (rtx, rtx, rtx_insn *);
 extern bool memory_tagging_p (void);
 extern rtx_insn *asan_emit_stack_protection (rtx, rtx, unsigned int,
 					     HOST_WIDE_INT *, tree *, int);
diff --git a/gcc/asan.c b/gcc/asan.c
index d361b4b562f75cb0c2e081218073eacb3704f8d0..0e74e32ae6ca4e130b3f13abe110364b119def46 100644
--- a/gcc/asan.c
+++ b/gcc/asan.c
@@ -3836,6 +3836,46 @@ hwasan_emit_prologue (rtx *bases,
     }
 }
 
+rtx_insn *
+hwasan_emit_uncolour_frame (rtx dynamic, rtx vars, rtx_insn *before)
+{
+  if (before)
+    push_to_sequence (before);
+  else
+    start_sequence ();
+
+  dynamic = convert_memory_address (ptr_mode, dynamic);
+  vars = convert_memory_address (ptr_mode, vars);
+
+  rtx top_rtx;
+  rtx bot_rtx;
+  if (STACK_GROWS_DOWNWARD)
+    {
+      top_rtx = vars;
+      bot_rtx = dynamic;
+    }
+  else
+    {
+      top_rtx = dynamic;
+      bot_rtx = vars;
+    }
+
+  rtx size_rtx = expand_simple_binop (Pmode, MINUS, top_rtx, bot_rtx,
+				  NULL_RTX, /* unsignedp = */0, OPTAB_DIRECT);
+
+  /* TODO Other options (i.e. inline options)  */
+  rtx ret = init_one_libfunc ("__hwasan_tag_memory");
+  emit_library_call (ret, LCT_NORMAL, VOIDmode,
+      bot_rtx, ptr_mode,
+      const0_rtx, QImode,
+      size_rtx, ptr_mode);
+
+  do_pending_stack_adjust ();
+  rtx_insn *insns = get_insns ();
+  end_sequence ();
+  return insns;
+}
+
 rtx
 hwasan_create_untagged_base (rtx orig_base)
 {
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index aacf210facc462675a980ee87bd38d4a7d94ad09..9f0872b32354cbc3186f3f2d2600f711a46926d1 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -2412,6 +2412,14 @@ expand_used_vars (void)
     var_end_seq = asan_emit_allocas_unpoison (virtual_stack_dynamic_rtx,
 					      virtual_stack_vars_rtx,
 					      var_end_seq);
+  /* Here we uncolour the entire frame for this function.
+     We need to uncolour *something* if either we have coloured some local
+     variables or we have coloured some alloca objects.  */
+  else if (memory_tagging_p ()
+	   && (cfun->calls_alloca || stack_vars_num > 0))
+    var_end_seq = hwasan_emit_uncolour_frame (virtual_stack_dynamic_rtx,
+					      virtual_stack_vars_rtx,
+					      var_end_seq);
 
   fini_vars_expansion ();