diff --git a/bazel/upb_proto_library.bzl b/bazel/upb_proto_library.bzl
index d4d51604f4..bec5d9cbd1 100644
--- a/bazel/upb_proto_library.bzl
+++ b/bazel/upb_proto_library.bzl
@@ -21,23 +21,17 @@ def _get_real_short_path(file):
 
     # Sometimes it has another few prefixes like:
     #   _virtual_imports/any_proto/google/protobuf/any.proto
+    #   benchmarks/_virtual_imports/100_msgs_proto/benchmarks/100_msgs.proto
     # We want just google/protobuf/any.proto.
-    if short_path.startswith("_virtual_imports"):
-        short_path = short_path.split("/", 2)[-1]
+    virtual_imports = "_virtual_imports/"
+    if virtual_imports in short_path:
+        short_path = short_path.split(virtual_imports)[1].split("/", 1)[1]
     return short_path
 
 def _get_real_root(file):
     real_short_path = _get_real_short_path(file)
     return file.path[:-len(real_short_path) - 1]
 
-def _get_real_roots(files):
-    roots = {}
-    for file in files:
-        real_root = _get_real_root(file)
-        if real_root:
-            roots[real_root] = True
-    return roots.keys()
-
 def _generate_output_file(ctx, src, extension):
     real_short_path = _get_real_short_path(src)
     real_short_path = paths.relativize(real_short_path, ctx.label.package)
diff --git a/benchmarks/BUILD b/benchmarks/BUILD
index a937accc9a..5c32e10444 100644
--- a/benchmarks/BUILD
+++ b/benchmarks/BUILD
@@ -7,23 +7,24 @@ load(
     ":build_defs.bzl",
     "tmpl_cc_binary",
     "cc_lite_proto_library",
+    "expand_suffixes",
 )
 
 licenses(["notice"])
 
 proto_library(
-    name = "benchmark_descriptor_proto",
+    name = "descriptor_proto",
     srcs = ["descriptor.proto"],
 )
 
 upb_proto_library(
     name = "benchmark_descriptor_upb_proto",
-    deps = [":benchmark_descriptor_proto"],
+    deps = [":descriptor_proto"],
 )
 
 upb_proto_reflection_library(
     name = "benchmark_descriptor_upb_proto_reflection",
-    deps = [":benchmark_descriptor_proto"],
+    deps = [":descriptor_proto"],
 )
 
 upb_proto_reflection_library(
@@ -33,7 +34,7 @@ upb_proto_reflection_library(
 
 cc_proto_library(
     name = "benchmark_descriptor_cc_proto",
-    deps = [":benchmark_descriptor_proto"],
+    deps = [":descriptor_proto"],
 )
 
 proto_library(
@@ -69,26 +70,65 @@ cc_binary(
 SIZE_BENCHMARKS = {
     "empty": "Empty",
     "descriptor": "FileDescriptorSet",
-    "100_msgs": "Message99",
+    "100_msgs": "Message100",
+    "200_msgs": "Message200",
+    "100_fields": "Message",
+    "200_fields": "Message",
 }
 
 py_binary(
-    name = "gen_benchmark_proto",
-    srcs = ["gen_benchmark_proto.py"],
+    name = "gen_synthetic_protos",
+    srcs = ["gen_synthetic_protos.py"],
+)
+
+py_binary(
+    name = "gen_upb_binary_c",
+    srcs = ["gen_upb_binary_c.py"],
+)
+
+py_binary(
+    name = "gen_protobuf_binary_cc",
+    srcs = ["gen_protobuf_binary_cc.py"],
 )
 
 genrule(
-    name = "gen_100_msgs",
-    tools = [":gen_benchmark_proto"],
-    outs = ["100_msgs.proto"],
-    cmd = "$(execpath :gen_benchmark_proto) $@",
+    name = "do_gen_synthetic_protos",
+    tools = [":gen_synthetic_protos"],
+    outs = [
+        "100_msgs.proto",
+        "200_msgs.proto",
+        "100_fields.proto",
+        "200_fields.proto",
+    ],
+    cmd = "$(execpath :gen_synthetic_protos) $(GENDIR)",
 )
 
-[(
 proto_library(
-    name = k + "_proto",
-    srcs = [k + ".proto"],
-),
+    name = "100_msgs_proto",
+    srcs = ["100_msgs.proto"],
+)
+
+proto_library(
+    name = "200_msgs_proto",
+    srcs = ["200_msgs.proto"],
+)
+
+proto_library(
+    name = "100_fields_proto",
+    srcs = ["100_fields.proto"],
+)
+
+proto_library(
+    name = "200_fields_proto",
+    srcs = ["200_fields.proto"],
+)
+
+proto_library(
+    name = "empty_proto",
+    srcs = ["empty.proto"],
+)
+
+[(
 upb_proto_library(
     name = k + "_upb_proto",
     deps = [":" + k + "_proto"],
@@ -100,11 +140,11 @@ cc_proto_library(
 tmpl_cc_binary(
     name = k + "_upb_binary",
     testonly = 1,
-    srcs = ["upb_binary.c.tmpl"],
-    replacements = {
-        "PROTO": "upb_benchmark_" + v,
-        "INCLUDE": "benchmarks/" + k + ".upb.h",
-    },
+    gen = ":gen_upb_binary_c",
+    args = [
+        "benchmarks/" + k + ".upb.h", 
+        "upb_benchmark_" + v,
+    ],
     deps = [
         ":" + k + "_upb_proto",
     ],
@@ -112,11 +152,11 @@ tmpl_cc_binary(
 tmpl_cc_binary(
     name = k + "_protobuf_binary",
     testonly = 1,
-    srcs = ["protobuf_binary.cc.tmpl"],
-    replacements = {
-        "PROTO": "upb_benchmark::" + v,
-        "INCLUDE": "benchmarks/" + k + ".pb.h",
-    },
+    gen = ":gen_protobuf_binary_cc",
+    args = [
+        "benchmarks/" + k + ".pb.h",
+        "upb_benchmark::" + v,
+    ],
     deps = [
         ":" + k + "_cc_proto",
     ],
@@ -129,13 +169,23 @@ cc_lite_proto_library(
 tmpl_cc_binary(
     name = k + "_lite_protobuf_binary",
     testonly = 1,
-    srcs = ["protobuf_binary.cc.tmpl"],
-    replacements = {
-        "PROTO": "upb_benchmark::" + v,
-        "INCLUDE": "benchmarks/" + k + "_lite.pb.h",
-    },
+    gen = ":gen_protobuf_binary_cc",
+    args = [
+        "benchmarks/" + k + "_lite.pb.h",
+        "upb_benchmark::" + v,
+    ],
     deps = [
         ":" + k + "_cc_lite_proto",
     ],
 )) for k, v in SIZE_BENCHMARKS.items()]
 
+genrule(
+    testonly = 1,
+    name = "size_data",
+    srcs = expand_suffixes(
+        SIZE_BENCHMARKS.keys(),
+        suffixes = ["_upb_binary", "_protobuf_binary"],
+    ),
+    outs = ["size_data.txt"],
+    cmd = "size --format=GNU -d $(SRCS) > $@",
+)
diff --git a/benchmarks/build_defs.bzl b/benchmarks/build_defs.bzl
index 402a523db2..157be4d03b 100644
--- a/benchmarks/build_defs.bzl
+++ b/benchmarks/build_defs.bzl
@@ -1,24 +1,16 @@
 
-def tmpl_cc_binary(name, srcs, replacements = [], **kwargs):
-    if len(srcs) != 1:
-        fail("Currently srcs must have exactly 1 element")
-    src = srcs[0]
-    if not src.endswith(".tmpl"):
-        fail("srcs of tmpl_cc_binary must end with .tmpl")
-    outs = [name + "_" + src[:-5]]
-    sed_cmds = ["s,{},{},g".format(k, v) for k, v in replacements.items()]
-    cmd = "sed -e '{}' $< > $@".format("; ".join(sed_cmds))
-
+def tmpl_cc_binary(name, gen, args, replacements = [], **kwargs):
+    srcs = [name + ".cc"]
     native.genrule(
         name = name + "_gen_srcs",
-        srcs = [src],
-        outs = outs,
-        cmd = cmd,
+        tools = [gen],
+        outs = srcs,
+        cmd = "$(location " + gen + ") " + " ".join(args) + " > $@",
     )
 
     native.cc_binary(
         name = name,
-        srcs = outs,
+        srcs = srcs,
         **kwargs,
     )
 
@@ -42,3 +34,10 @@ def cc_lite_proto_library(name, srcs, outs):
         name = name,
         deps = [":" + name + "_proto"],
     )
+
+def expand_suffixes(vals, suffixes):
+  ret = []
+  for val in vals:
+    for suffix in suffixes:
+      ret.append(val + suffix)
+  return ret
diff --git a/benchmarks/descriptor.proto b/benchmarks/descriptor.proto
index a95371d4da..b69b27f89e 100644
--- a/benchmarks/descriptor.proto
+++ b/benchmarks/descriptor.proto
@@ -48,10 +48,6 @@ option csharp_namespace = "Google.Protobuf.Reflection";
 option objc_class_prefix = "GPB";
 option cc_enable_arenas = true;
 
-// descriptor.proto must be optimized for speed because reflection-based
-// algorithms don't work during bootstrapping.
-option optimize_for = SPEED;
-
 // The protocol compiler can output a FileDescriptorSet containing the .proto
 // files it parses.
 message FileDescriptorSet {
diff --git a/benchmarks/descriptor_sv.proto b/benchmarks/descriptor_sv.proto
index c595a68649..8ca0888da7 100644
--- a/benchmarks/descriptor_sv.proto
+++ b/benchmarks/descriptor_sv.proto
@@ -47,10 +47,6 @@ option csharp_namespace = "Google.Protobuf.Reflection";
 option objc_class_prefix = "GPB";
 option cc_enable_arenas = true;
 
-// descriptor.proto must be optimized for speed because reflection-based
-// algorithms don't work during bootstrapping.
-option optimize_for = SPEED;
-
 // The protocol compiler can output a FileDescriptorSet containing the .proto
 // files it parses.
 message FileDescriptorSet {
diff --git a/benchmarks/gen_protobuf_binary_cc.py b/benchmarks/gen_protobuf_binary_cc.py
new file mode 100644
index 0000000000..181cafcde8
--- /dev/null
+++ b/benchmarks/gen_protobuf_binary_cc.py
@@ -0,0 +1,38 @@
+
+import sys
+import re
+
+include = sys.argv[1]
+msg_basename = sys.argv[2]
+count = 1
+
+m = re.search(r'(.*\D)(\d+)$', sys.argv[2])
+if m:
+  msg_basename = m.group(1)
+  count = int(m.group(2))
+
+print(f'''
+#include "{include}"
+
+char buf[1];
+
+int main() {{
+''')
+
+def RefMessage(name):
+  print(f'''
+  {{
+    {name} proto;
+    proto.ParseFromArray(buf, 0);
+    proto.SerializePartialToArray(&buf[0], 0);
+  }}
+  ''')
+
+RefMessage(msg_basename)
+
+for i in range(2, count + 1):
+  RefMessage(msg_basename + str(i))
+
+print('''
+  return 0;
+}''')
diff --git a/benchmarks/gen_synthetic_protos.py b/benchmarks/gen_synthetic_protos.py
new file mode 100644
index 0000000000..36d1f7d7a7
--- /dev/null
+++ b/benchmarks/gen_synthetic_protos.py
@@ -0,0 +1,85 @@
+
+import sys
+import random
+
+base = sys.argv[1]
+
+field_freqs = [
+    (('bool', 'optional'), 8.321),
+    (('bool', 'repeated'), 0.033),
+    (('bytes', 'optional'), 0.809),
+    (('bytes', 'repeated'), 0.065),
+    (('double', 'optional'), 2.845),
+    (('double', 'repeated'), 0.143),
+    (('fixed32', 'optional'), 0.084),
+    (('fixed32', 'repeated'), 0.012),
+    (('fixed64', 'optional'), 0.204),
+    (('fixed64', 'repeated'), 0.027),
+    (('float', 'optional'), 2.355),
+    (('float', 'repeated'), 0.132),
+    (('int32', 'optional'), 6.717),
+    (('int32', 'repeated'), 0.366),
+    (('int64', 'optional'), 9.678),
+    (('int64', 'repeated'), 0.425),
+    (('sfixed32', 'optional'), 0.018),
+    (('sfixed32', 'repeated'), 0.005),
+    (('sfixed64', 'optional'), 0.022),
+    (('sfixed64', 'repeated'), 0.005),
+    (('sint32', 'optional'), 0.026),
+    (('sint32', 'repeated'), 0.009),
+    (('sint64', 'optional'), 0.018),
+    (('sint64', 'repeated'), 0.006),
+    (('string', 'optional'), 25.461),
+    (('string', 'repeated'), 2.606),
+    (('Enum', 'optional'), 6.16),
+    (('Enum', 'repeated'), 0.576),
+    (('Message', 'optional'), 22.472),
+    (('Message', 'repeated'), 7.766),
+    (('uint32', 'optional'), 1.289),
+    (('uint32', 'repeated'), 0.051),
+    (('uint64', 'optional'), 1.044),
+    (('uint64', 'repeated'), 0.079),
+]
+
+population = [item[0] for item in field_freqs]
+weights = [item[1] for item in field_freqs]
+
+with open(base + "/benchmarks/100_msgs.proto", "w") as f:
+  f.write('syntax = "proto3";\n')
+  f.write('package upb_benchmark;\n')
+  f.write('message Message {}\n')
+  for i in range(2, 101):
+    f.write(f'message Message{i} {{}}\n')
+
+with open(base + "/benchmarks/200_msgs.proto", "w") as f:
+  f.write('syntax = "proto3";\n')
+  f.write('package upb_benchmark;\n')
+  f.write('message Message {}\n')
+  for i in range(2, 501):
+    f.write(f'message Message{i} {{}}\n')
+
+with open(base + "/benchmarks/100_fields.proto", "w") as f:
+  f.write('syntax = "proto2";\n')
+  f.write('package upb_benchmark;\n')
+  f.write('enum Enum { ZERO = 0; }\n')
+  f.write('message Message {\n')
+  i = 1
+  random.seed(a=0, version=2)
+  for field in random.choices(population=population, weights=weights, k=100):
+    field_type, label = field
+    f.write(f'  {label} {field_type} field{i} = {i};\n')
+    i += 1
+  f.write('}\n')
+
+with open(base + "/benchmarks/200_fields.proto", "w") as f:
+  f.write('syntax = "proto2";\n')
+  f.write('package upb_benchmark;\n')
+  f.write('enum Enum { ZERO = 0; }\n')
+  f.write('message Message {\n')
+  i = 1
+  random.seed(a=0, version=2)
+  for field in random.choices(population=population, weights=weights, k=200):
+    field_type, label = field
+    f.write(f'  {label} {field_type} field{i} = {i};\n')
+    i += 1
+  f.write('}\n')
diff --git a/benchmarks/gen_upb_binary_c.py b/benchmarks/gen_upb_binary_c.py
new file mode 100644
index 0000000000..430d8c45c9
--- /dev/null
+++ b/benchmarks/gen_upb_binary_c.py
@@ -0,0 +1,39 @@
+
+import sys
+import re
+
+include = sys.argv[1]
+msg_basename = sys.argv[2]
+count = 1
+
+m = re.search(r'(.*\D)(\d+)$', sys.argv[2])
+if m:
+  msg_basename = m.group(1)
+  count = int(m.group(2))
+
+print(f'''
+#include "{include}"
+
+char buf[1];
+
+int main() {{
+  upb_arena *arena = upb_arena_new();
+  size_t size;
+''')
+
+def RefMessage(name):
+  print(f'''
+  {{
+    {name} *proto = {name}_parse(buf, 1, arena);
+    {name}_serialize(proto, arena, &size);
+  }}
+  ''')
+
+RefMessage(msg_basename)
+
+for i in range(2, count + 1):
+  RefMessage(msg_basename + str(i))
+
+print('''
+  return 0;
+}''')
diff --git a/benchmarks/protobuf_binary.cc.tmpl b/benchmarks/protobuf_binary.cc.tmpl
deleted file mode 100644
index 139ad7433c..0000000000
--- a/benchmarks/protobuf_binary.cc.tmpl
+++ /dev/null
@@ -1,10 +0,0 @@
-
-#include "INCLUDE"
-
-char buf[1];
-
-int main() {
-  PROTO proto;
-  proto.ParseFromArray(buf, 1);
-  proto.SerializeToArray(buf, 1);
-}
diff --git a/benchmarks/upb_binary.c.tmpl b/benchmarks/upb_binary.c.tmpl
deleted file mode 100644
index 6f2904bbd6..0000000000
--- a/benchmarks/upb_binary.c.tmpl
+++ /dev/null
@@ -1,12 +0,0 @@
-
-#include "INCLUDE"
-
-char buf[1];
-
-int main() {
-  upb_arena *arena = upb_arena_new();
-  size_t size;
-  PROTO *proto = PROTO_parse(buf, 1, arena);
-  PROTO_serialize(proto, arena, &size);
-  return 0;
-}