diff --git a/upb/mini_table/internal/message.c b/upb/mini_table/internal/message.c
index f278b36577..2f23df4118 100644
--- a/upb/mini_table/internal/message.c
+++ b/upb/mini_table/internal/message.c
@@ -14,7 +14,12 @@
 // Must be last.
 #include "upb/port/def.inc"
 
-// A MiniTable for an empty message, used for unlinked sub-messages.
+// A MiniTable for an empty message, used for unlinked sub-messages that are
+// built via MiniDescriptors.  Messages that use this MiniTable may possibly
+// be linked later, in which case this MiniTable will be replaced with a real
+// one.  This pattern is known as "dynamic tree shaking", and it introduces
+// complication because sub-messages may either be the "empty" type or the
+// "real" type.  A tagged bit indicates the difference.
 const struct upb_MiniTable UPB_PRIVATE(_kUpb_MiniTable_Empty) = {
     .UPB_PRIVATE(subs) = NULL,
     .UPB_PRIVATE(fields) = NULL,
@@ -25,3 +30,18 @@ const struct upb_MiniTable UPB_PRIVATE(_kUpb_MiniTable_Empty) = {
     .UPB_PRIVATE(table_mask) = -1,
     .UPB_PRIVATE(required_count) = 0,
 };
+
+// A MiniTable for a statically tree shaken message.  Messages that use this
+// MiniTable are guaranteed to remain unlinked; unlike the empty message, this
+// MiniTable is never replaced, which greatly simplifies everything, because the
+// type of a sub-message is always known, without consulting a tagged bit.
+const struct upb_MiniTable UPB_PRIVATE(_kUpb_MiniTable_StaticallyTreeShaken) = {
+    .UPB_PRIVATE(subs) = NULL,
+    .UPB_PRIVATE(fields) = NULL,
+    .UPB_PRIVATE(size) = sizeof(struct upb_Message),
+    .UPB_PRIVATE(field_count) = 0,
+    .UPB_PRIVATE(ext) = kUpb_ExtMode_NonExtendable,
+    .UPB_PRIVATE(dense_below) = 0,
+    .UPB_PRIVATE(table_mask) = -1,
+    .UPB_PRIVATE(required_count) = 0,
+};
diff --git a/upb_generator/bootstrap_compiler.bzl b/upb_generator/bootstrap_compiler.bzl
index 4a3bd8ccdd..e92fbafe75 100644
--- a/upb_generator/bootstrap_compiler.bzl
+++ b/upb_generator/bootstrap_compiler.bzl
@@ -126,7 +126,14 @@ def _cmake_staleness_test(name, base_dir, src_files, proto_lib_deps, **kwargs):
             name = name + "_copy_gencode_%d" % genrule,
             outs = ["generated_sources/" + src],
             srcs = [name, name + "_minitable"],
-            cmd = "mkdir -p $(@D); for src in $(SRCS); do cp -f $$src $(@D) || echo 'copy failed!'; done",
+            cmd = """
+                mkdir -p $(@D)
+                for src in $(SRCS); do
+                    if [[ $$src == *%s ]]; then
+                        cp -f $$src $(@D) || echo 'copy failed!'
+                    fi
+                done
+            """ % src[src.rfind("/"):],
         )
 
     # Keep bazel gencode in sync with our checked-in sources needed for cmake builds.
diff --git a/upb_generator/protoc-gen-upb_minitable.cc b/upb_generator/protoc-gen-upb_minitable.cc
index 2ed83dd1c1..dbc959f82f 100644
--- a/upb_generator/protoc-gen-upb_minitable.cc
+++ b/upb_generator/protoc-gen-upb_minitable.cc
@@ -367,8 +367,8 @@ void WriteMessage(upb::MessageDefPtr message, const DefPoolPair& pools,
           IsCrossFile(field)) {
         if (seen.insert(pools.GetMiniTable64(field.message_type())).second) {
           output(
-              "__attribute__((weak)) const upb_MiniTable* $0 = "
-              "&UPB_PRIVATE(_kUpb_MiniTable_Empty);\n",
+              "__attribute__((weak)) const upb_MiniTable* $0 ="
+              " &UPB_PRIVATE(_kUpb_MiniTable_StaticallyTreeShaken);\n",
               MessagePtrName(field.message_type()));
         }
       }
@@ -571,7 +571,7 @@ void WriteMiniTableSourceIncludes(upb::FileDefPtr file, Output& output) {
 
   output(
       "extern const struct upb_MiniTable "
-      "UPB_PRIVATE(_kUpb_MiniTable_Empty);\n");
+      "UPB_PRIVATE(_kUpb_MiniTable_StaticallyTreeShaken);\n");
 }
 
 void WriteMiniTableSource(const DefPoolPair& pools, upb::FileDefPtr file,