diff --git a/.travis.yml b/.travis.yml
index 917aa91e3e..b1a0cc765d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,3 +11,4 @@ env:
   - UPB_TRAVIS_BUILD=lua
   - UPB_TRAVIS_BUILD=coverage
   - UPB_TRAVIS_BUILD=warnings
+  - UPB_TRAVIS_BUILD=genfiles
diff --git a/Makefile b/Makefile
index e75fe54c51..7d1ef11202 100644
--- a/Makefile
+++ b/Makefile
@@ -95,16 +95,19 @@ clean_leave_profile:
 	@rm -rf obj lib
 	@rm -f tests/google_message?.h
 	@rm -f $(TESTS) tests/testmain.o tests/t.*
-	@rm -f upb/descriptor.pb
+	@rm -f upb/descriptor/descriptor.pb
 	@rm -rf tools/upbc deps
 	@rm -rf upb/bindings/python/build
 	@rm -f upb/bindings/ruby/Makefile
 	@rm -f upb/bindings/ruby/upb.o
 	@rm -f upb/bindings/ruby/upb.so
 	@rm -f upb/bindings/ruby/mkmf.log
+	@rm -f tests/google_messages.pb.*
+	@rm -f tests/google_messages.proto.pb
+	@rm -f upb.c upb.h
 	@find . | grep dSYM | xargs rm -rf
 
-clean: clean_leave_profile
+clean: clean_leave_profile clean_lua
 	@rm -rf $(call rwildcard,,*.gcno) $(call rwildcard,,*.gcda)
 
 # A little bit of Make voodoo: you can call this from the deps of a patterned
@@ -166,8 +169,20 @@ upb_json_SRCS = \
   upb/json/parser.c \
   upb/json/printer.c \
 
-upb/json/parser.c: upb/json/parser.rl
-	$(E) RAGEL $<
+# Ideally we could keep this uncommented, but Git apparently sometimes skews
+# timestamps slightly at "clone" time, which makes "Make" think that it needs
+# to rebuild upb/json/parser.c when it actually doesn't.  This would be harmless
+# except that the user might not have Ragel installed.
+#
+# So instead we require an excplicit "make ragel" to rebuild this (for now).
+# More pain for people developing upb/json/parser.rl, but less pain for everyone
+# else.
+#
+# upb/json/parser.c: upb/json/parser.rl
+# 	$(E) RAGEL $<
+# 	$(Q) ragel -C -o upb/json/parser.c upb/json/parser.rl
+ragel:
+	$(E) RAGEL upb/json/parser.rl
 	$(Q) ragel -C -o upb/json/parser.c upb/json/parser.rl
 
 # If the user doesn't specify an -O setting, we use -O3 for critical-path
@@ -219,13 +234,24 @@ upb/descriptor/descriptor.pb: upb/descriptor/descriptor.proto
 	@# TODO: replace with upbc
 	protoc upb/descriptor/descriptor.proto -oupb/descriptor/descriptor.pb
 
-descriptorgen: upb/descriptor/descriptor.pb tools/upbc
-	@# Regenerate descriptor_const.h
-	./tools/upbc -o upb/descriptor/descriptor upb/descriptor/descriptor.pb
-
-tools/upbc: tools/upbc.c $(LIBUPB)
-	$(E) CC $<
-	$(Q) $(CC) $(CFLAGS) $(CPPFLAGS) -o $@ $< $(LIBUPB)
+genfiles: upb/descriptor/descriptor.pb tools/upbc
+	./tools/upbc upb/descriptor/descriptor.pb upb/descriptor/descriptor google_protobuf_descriptor
+	lua dynasm/dynasm.lua upb/pb/compile_decoder_x64.dasc > upb/pb/compile_decoder_x64.h || (rm upb/pb/compile_decoder_x64.h ; false)
+
+# upbc depends on these Lua extensions.
+UPBC_LUA_EXTS = \
+  upb/bindings/lua/upb_c.so \
+  upb/bindings/lua/upb/pb_c.so \
+  upb/bindings/lua/upb/table_c.so \
+
+tools/upbc: $(UPBC_LUA_EXTS) Makefile
+	$(E) ECHO tools/upbc
+	$(Q) echo "#!/bin/sh" > tools/upbc
+	$(Q) echo 'BASE=`dirname "$$0"`' >> tools/upbc
+	$(Q) echo 'export LUA_CPATH="$$BASE/../upb/bindings/lua/?.so"' >> tools/upbc
+	$(Q) echo 'export LUA_PATH="$$BASE/?.lua;$$BASE/../upb/bindings/lua/?.lua"' >> tools/upbc
+	$(Q) echo 'lua $$BASE/upbc.lua "$$@"' >> tools/upbc
+	$(Q) chmod a+x tools/upbc
 
 examples/msg: examples/msg.c $(LIBUPB)
 	$(E) CC $<
@@ -379,14 +405,14 @@ tests/bindings/googlepb/test_vs_proto2.googlemessage2: $(GOOGLEPB_TEST_DEPS) \
 # Lua extension ##################################################################
 
 ifeq ($(shell uname), Darwin)
-  LUA_LDFLAGS = -undefined dynamic_lookup
+  LUA_LDFLAGS = -undefined dynamic_lookup -flat_namespace
 else
   LUA_LDFLAGS =
 endif
 
 LUAEXTS = \
-  upb/bindings/lua/upb.so \
-  upb/bindings/lua/upb/pb.so \
+  upb/bindings/lua/upb_c.so \
+  upb/bindings/lua/upb/pb_c.so \
 
 LUATESTS = \
   tests/bindings/lua/test_upb.lua \
@@ -398,23 +424,19 @@ testlua: lua
 	@set -e  # Abort on error.
 	@for test in $(LUATESTS) ; do \
 	  echo LUA $$test; \
-	  LUA_PATH="tests/bindings/lua/lunit/?.lua" \
+	  LUA_PATH="tests/bindings/lua/lunit/?.lua;upb/bindings/lua/?.lua" \
 	    LUA_CPATH=upb/bindings/lua/?.so \
 	    lua $$test; \
 	done
 
 clean: clean_lua
 clean_lua:
-	@rm -f upb/bindings/lua/upb.lua.h
-	@rm -f upb/bindings/lua/upb.so
-	@rm -f upb/bindings/lua/upb/pb.so
+	@rm -f upb/bindings/lua/upb_c.so
+	@rm -f upb/bindings/lua/upb/pb_c.so
+	@rm -f upb/bindings/lua/upb/table_c.so
 
 lua: $(LUAEXTS)
 
-upb/bindings/lua/upb.lua.h:
-	$(E) XXD upb/bindings/lua/upb.lua
-	$(Q) xxd -i < upb/bindings/lua/upb.lua > upb/bindings/lua/upb.lua.h
-
 # Right now the core upb module depends on all of these.
 # It's a TODO to factor this more cleanly in the code.
 LUA_LIB_DEPS = \
@@ -422,22 +444,17 @@ LUA_LIB_DEPS = \
   lib/libupb.descriptor_pic.a \
   lib/libupb_pic.a \
 
-upb/bindings/lua/upb.so: upb/bindings/lua/upb.c upb/bindings/lua/upb.lua.h $(LUA_LIB_DEPS)
+upb/bindings/lua/upb_c.so: upb/bindings/lua/upb.c $(LUA_LIB_DEPS)
 	$(E) CC upb/bindings/lua/upb.c
 	$(Q) $(CC) $(OPT) $(WARNFLAGS) $(CPPFLAGS) $(CFLAGS) -fpic -shared -o $@ $< $(LUA_LDFLAGS) $(LUA_LIB_DEPS)
 
-# TODO: the dependency between upb/pb.so and upb.so is expressed at the
-# .so level, which means that the OS will try to load upb.so when upb/pb.so
-# is loaded.  This is what we want, but getting the paths right is tricky.
-# Basically the dynamic linker needs to be able to find upb.so at:
-#   $(LD_LIBRARY_PATH)/upb/bindings/lua/upb.so
-# So the user has to set both LD_LIBRARY_PATH and LUA_CPATH correctly.
-# Another option would be to require the Lua program to always require
-# "upb" before requiring eg. "upb.pb", and then the dependency would not
-# be expressed at the .so level.
-upb/bindings/lua/upb/pb.so: upb/bindings/lua/upb/pb.c upb/bindings/lua/upb.so
-	$(E) CC upb/bindings/lua/upb.pb.c
-	$(Q) $(CC) $(OPT) $(WARNFLAGS) $(CPPFLAGS) $(CFLAGS) -fpic -shared -o $@ $< upb/bindings/lua/upb.so $(LUA_LDFLAGS)
+upb/bindings/lua/upb/table_c.so: upb/bindings/lua/upb/table.c lib/libupb_pic.a
+	$(E) CC upb/bindings/lua/upb/table.c
+	$(Q) $(CC) $(OPT) $(WARNFLAGS) $(CPPFLAGS) $(CFLAGS) -fpic -shared -o $@ $< $(LUA_LDFLAGS)
+
+upb/bindings/lua/upb/pb_c.so: upb/bindings/lua/upb/pb.c $(LUA_LIB_DEPS)
+	$(E) CC upb/bindings/lua/upb/pb.c
+	$(Q) $(CC) $(OPT) $(WARNFLAGS) $(CPPFLAGS) $(CFLAGS) -fpic -shared -o $@ $< $(LUA_LDFLAGS)
 
 
 # Python extension #############################################################
diff --git a/tests/bindings/lua/test_upb.pb.lua b/tests/bindings/lua/test_upb.pb.lua
index 02b443a662..7c1c0d0606 100644
--- a/tests/bindings/lua/test_upb.pb.lua
+++ b/tests/bindings/lua/test_upb.pb.lua
@@ -1,6 +1,8 @@
 
-local upb = require "upb"
+-- Require "pb" first to ensure that the transitive require of "upb" is
+-- handled properly by the "pb" module.
 local pb = require "upb.pb"
+local upb = require "upb"
 local lunit = require "lunit"
 
 if _VERSION >= 'Lua 5.2' then
diff --git a/tools/dump_cinit.lua b/tools/dump_cinit.lua
index 13e1f52ecb..dac2498dd7 100644
--- a/tools/dump_cinit.lua
+++ b/tools/dump_cinit.lua
@@ -10,7 +10,7 @@
 
 --]]
 
-local upbtable = require "upbtable"
+local upbtable = require "upb.table"
 local upb = require "upb"
 local export = {}
 
diff --git a/tools/upbc.lua b/tools/upbc.lua
index f68d25fe2c..955da57d3b 100644
--- a/tools/upbc.lua
+++ b/tools/upbc.lua
@@ -19,6 +19,12 @@ local upb = require "upb"
 local src = arg[1]
 local outbase = arg[2]
 local basename = arg[3]
+
+if not (src and outbase and basename) then
+  print("Usage: upbc <binary descriptor> <output filename base> <symbol prefix>")
+  return 1
+end
+
 local hfilename = outbase .. ".upb.h"
 local cfilename = outbase .. ".upb.c"
 
diff --git a/travis.sh b/travis.sh
index 502b2f1640..93a5935dc3 100755
--- a/travis.sh
+++ b/travis.sh
@@ -59,6 +59,21 @@ lua_script() {
   make -j12 testlua USER_CPPFLAGS=`pkg-config lua5.2 --cflags`
 }
 
+# Test that generated files don't need to be regenerated.
+#
+# We would include the Ragel output here too, but we can't really guarantee
+# that its output will be stable for multiple versions of the tool, and we
+# don't want the test to be brittle.
+genfiles_install() {
+  sudo apt-get update -qq
+  sudo apt-get install lua5.2 liblua5.2-dev protobuf-compiler
+}
+genfiles_script() {
+  make -j12 genfiles USER_CPPFLAGS=`pkg-config lua5.2 --cflags`
+  # Will fail if any differences were observed.
+  git diff --exit-code
+}
+
 # A run that executes with coverage support and uploads to coveralls.io
 coverage_install() {
   sudo apt-get update -qq
diff --git a/upb/bindings/lua/upb.c b/upb/bindings/lua/upb.c
index b35af24edd..aebf9f76be 100644
--- a/upb/bindings/lua/upb.c
+++ b/upb/bindings/lua/upb.c
@@ -33,10 +33,6 @@
 #include "upb/pb/glue.h"
 #include "upb/shim/shim.h"
 
-static const char upb_lua[] = {
-#include "upb/bindings/lua/upb.lua.h"
-};
-
 // Lua metatable types.
 #define LUPB_MSG "lupb.msg"
 #define LUPB_ARRAY "lupb.array"
@@ -1771,9 +1767,9 @@ static void lupb_setfieldi(lua_State *L, const char *field, int i) {
   lua_setfield(L, -2, field);
 }
 
-int luaopen_upb(lua_State *L) {
+int luaopen_upb_c(lua_State *L) {
   static char module_key;
-  if (lupb_openlib(L, &module_key, "upb", lupb_toplevel_m)) {
+  if (lupb_openlib(L, &module_key, "upb_c", lupb_toplevel_m)) {
     return 1;
   }
 
@@ -1858,14 +1854,5 @@ int luaopen_upb(lua_State *L) {
   lupb_setfieldi(L, "HANDLER_STARTSEQ",    UPB_HANDLER_STARTSEQ);
   lupb_setfieldi(L, "HANDLER_ENDSEQ",      UPB_HANDLER_ENDSEQ);
 
-  // Call the chunk that will define the extra functions on upb, passing our
-  // package dictionary as the argument.
-  if (luaL_loadbuffer(L, upb_lua, sizeof(upb_lua), "upb.lua") ||
-      lua_pcall(L, 0, LUA_MULTRET, 0)) {
-    lua_error(L);
-  }
-  lua_pushvalue(L, -2);
-  lua_call(L, 1, 0);
-
   return 1;  // Return package table.
 }
diff --git a/upb/bindings/lua/upb.lua b/upb/bindings/lua/upb.lua
index bda9dfee39..4090b37a6f 100644
--- a/upb/bindings/lua/upb.lua
+++ b/upb/bindings/lua/upb.lua
@@ -1,146 +1,156 @@
+--[[--------------------------------------------------------------------
+
+  upb - a minimalist implementation of protocol buffers.
+
+  Copyright (c) 2009 Google Inc.  See LICENSE for details.
+  Author: Josh Haberman <jhaberman@gmail.com>
+
+--------------------------------------------------------------------]]--
+
+-- Before calling require on "upb_c", we need to load the same library
+-- as RTLD_GLOBAL, for the benefit of other C extensions that depend on
+-- C functions in the core.
 --
--- upb - a minimalist implementation of protocol buffers.
---
--- Copyright (c) 2009 Google Inc.  See LICENSE for details.
--- Author: Josh Haberman <jhaberman@gmail.com>
+-- This has to happen *before* the require call, because if the module
+-- is loaded RTLD_LOCAL first, a subsequent load as RTLD_GLOBAL won't
+-- have the proper effect, at least on some platforms.
+package.loadlib(package.searchpath("upb_c", package.cpath), "*")
+
+local upb = require("upb_c")
+
+-- A convenience function for building/linking/freezing defs
+-- while maintaining their original order.
 --
--- Pure-Lua support functions that are part of the "upb" module.
--- This file is embedded and packaged into the "upb" C module binary -- it
--- should not be installed or used directly!
-
-return function(upb)
-  -- A convenience function for building/linking/freezing defs
-  -- while maintaining their original order.
-  --
-  -- Sample usage:
-  --   local m1, m2 = upb.build_defs{
-  --     upb.MessageDef{full_name = "M1", fields = {
-  --         upb.FieldDef{
-  --           name = "m2",
-  --           number = 1,
-  --           type = upb.TYPE_MESSAGE,
-  --           subdef_name = ".M2"
-  --         },
-  --       }
-  --     },
-  --     upb.MessageDef{full_name = "M2"}
-  --   }
-  upb.build_defs = function(defs)
-    upb.SymbolTable(defs)
-    -- Lua 5.2 puts unpack in the table library.
-    return (unpack or table.unpack)(defs)
-  end
+-- Sample usage:
+--   local m1, m2 = upb.build_defs{
+--     upb.MessageDef{full_name = "M1", fields = {
+--         upb.FieldDef{
+--           name = "m2",
+--           number = 1,
+--           type = upb.TYPE_MESSAGE,
+--           subdef_name = ".M2"
+--         },
+--       }
+--     },
+--     upb.MessageDef{full_name = "M2"}
+--   }
+upb.build_defs = function(defs)
+  upb.SymbolTable(defs)
+  -- Lua 5.2 puts unpack in the table library.
+  return (unpack or table.unpack)(defs)
+end
 
-  local ipairs_iter = function(array, last_index)
-    local next_index = last_index + 1
-    if next_index > #array then
-      return nil
-    end
-    return next_index, array[next_index]
+local ipairs_iter = function(array, last_index)
+  local next_index = last_index + 1
+  if next_index > #array then
+    return nil
   end
+  return next_index, array[next_index]
+end
 
-  -- For iterating over the indexes and values of a upb.Array.
-  --
-  -- for i, val in upb.ipairs(array) do
-  --   -- ...
-  -- end
-  upb.ipairs = function(array)
-    return ipairs_iter, array, 0
-  end
+-- For iterating over the indexes and values of a upb.Array.
+--
+-- for i, val in upb.ipairs(array) do
+--   -- ...
+-- end
+upb.ipairs = function(array)
+  return ipairs_iter, array, 0
+end
 
-  local set_named = function(obj, init)
-    for k, v in pairs(init) do
-      local func = obj["set_" .. k]
-      if not func then
-        error("Cannot set member: " .. k)
-      end
-      func(obj, v)
+local set_named = function(obj, init)
+  for k, v in pairs(init) do
+    local func = obj["set_" .. k]
+    if not func then
+      error("Cannot set member: " .. k)
     end
+    func(obj, v)
   end
+end
+
+-- Capture references to the functions we're wrapping.
+local RealFieldDef = upb.FieldDef
+local RealEnumDef = upb.EnumDef
+local RealMessageDef = upb.MessageDef
+local RealSymbolTable = upb.SymbolTable
 
-  -- Capture references to the functions we're wrapping.
-  local RealFieldDef = upb.FieldDef
-  local RealEnumDef = upb.EnumDef
-  local RealMessageDef = upb.MessageDef
-  local RealSymbolTable = upb.SymbolTable
-
-  -- FieldDef constructor; a wrapper around the real constructor that can
-  -- set initial properties.
-  --
-  -- User can specify initialization values like so:
-  --   upb.FieldDef{label=upb.LABEL_REQUIRED, name="my_field", number=5,
-  --                type=upb.TYPE_INT32, default_value=12, type_name="Foo"}
-  upb.FieldDef = function(init)
-    local f = RealFieldDef()
-
-    if init then
-      -- Other members are often dependent on type, so set that first.
-      if init.type then
-        f:set_type(init.type)
-        init.type = nil
-      end
-
-      set_named(f, init)
+-- FieldDef constructor; a wrapper around the real constructor that can
+-- set initial properties.
+--
+-- User can specify initialization values like so:
+--   upb.FieldDef{label=upb.LABEL_REQUIRED, name="my_field", number=5,
+--                type=upb.TYPE_INT32, default_value=12, type_name="Foo"}
+upb.FieldDef = function(init)
+  local f = RealFieldDef()
+
+  if init then
+    -- Other members are often dependent on type, so set that first.
+    if init.type then
+      f:set_type(init.type)
+      init.type = nil
     end
 
-    return f
+    set_named(f, init)
   end
 
+  return f
+end
 
-  -- MessageDef constructor; a wrapper around the real constructor that can
-  -- set initial properties.
-  --
-  -- User can specify initialization values like so:
-  --   upb.MessageDef{full_name="MyMessage", extstart=8000, fields={...}}
-  upb.MessageDef = function(init)
-    local m = RealMessageDef()
-
-    if init then
-      for _, f in pairs(init.fields or {}) do
-        m:add(f)
-      end
-      init.fields = nil
 
-      set_named(m, init)
+-- MessageDef constructor; a wrapper around the real constructor that can
+-- set initial properties.
+--
+-- User can specify initialization values like so:
+--   upb.MessageDef{full_name="MyMessage", extstart=8000, fields={...}}
+upb.MessageDef = function(init)
+  local m = RealMessageDef()
+
+  if init then
+    for _, f in pairs(init.fields or {}) do
+      m:add(f)
     end
+    init.fields = nil
 
-    return m
+    set_named(m, init)
   end
 
-  -- EnumDef constructor; a wrapper around the real constructor that can
-  -- set initial properties.
-  --
-  -- User can specify initialization values like so:
-  --   upb.EnumDef{full_name="MyEnum",
-  --     values={
-  --       {"FOO_VALUE_1", 1},
-  --       {"FOO_VALUE_2", 2}
-  --     }
-  --   }
-  upb.EnumDef = function(init)
-    local e = RealEnumDef()
-
-    if init then
-      for _, val in pairs(init.values or {}) do
-        e:add(val[1], val[2])
-      end
-      init.values = nil
-
-      set_named(e, init)
+  return m
+end
+
+-- EnumDef constructor; a wrapper around the real constructor that can
+-- set initial properties.
+--
+-- User can specify initialization values like so:
+--   upb.EnumDef{full_name="MyEnum",
+--     values={
+--       {"FOO_VALUE_1", 1},
+--       {"FOO_VALUE_2", 2}
+--     }
+--   }
+upb.EnumDef = function(init)
+  local e = RealEnumDef()
+
+  if init then
+    for _, val in pairs(init.values or {}) do
+      e:add(val[1], val[2])
     end
+    init.values = nil
 
-    return e
+    set_named(e, init)
   end
 
-  -- SymbolTable constructor; a wrapper around the real constructor that can
-  -- add an initial set of defs.
-  upb.SymbolTable = function(defs)
-    local s = RealSymbolTable()
+  return e
+end
 
-    if defs then
-      s:add(defs)
-    end
+-- SymbolTable constructor; a wrapper around the real constructor that can
+-- add an initial set of defs.
+upb.SymbolTable = function(defs)
+  local s = RealSymbolTable()
 
-    return s
+  if defs then
+    s:add(defs)
   end
+
+  return s
 end
+
+return upb
diff --git a/upb/bindings/lua/upb/pb.c b/upb/bindings/lua/upb/pb.c
index 920648f0ec..bf82a9b962 100644
--- a/upb/bindings/lua/upb/pb.c
+++ b/upb/bindings/lua/upb/pb.c
@@ -92,11 +92,9 @@ static const struct luaL_Reg toplevel_m[] = {
   {NULL, NULL}
 };
 
-int luaopen_upb_pb(lua_State *L) {
-  luaopen_upb(L);
-
+int luaopen_upb_pb_c(lua_State *L) {
   static char module_key;
-  if (lupb_openlib(L, &module_key, "upb.pb", toplevel_m)) {
+  if (lupb_openlib(L, &module_key, "upb.pb_c", toplevel_m)) {
     return 1;
   }
 
diff --git a/upb/bindings/lua/upb/pb.lua b/upb/bindings/lua/upb/pb.lua
new file mode 100644
index 0000000000..66b39097ef
--- /dev/null
+++ b/upb/bindings/lua/upb/pb.lua
@@ -0,0 +1,11 @@
+--[[--------------------------------------------------------------------
+
+  upb - a minimalist implementation of protocol buffers.
+
+  Copyright (c) 2009 Google Inc.  See LICENSE for details.
+  Author: Josh Haberman <jhaberman@gmail.com>
+
+--------------------------------------------------------------------]]--
+
+require "upb"
+return require "upb.pb_c"
diff --git a/upb/bindings/lua/table.c b/upb/bindings/lua/upb/table.c
similarity index 99%
rename from upb/bindings/lua/table.c
rename to upb/bindings/lua/upb/table.c
index e15382bce0..0907f581aa 100644
--- a/upb/bindings/lua/table.c
+++ b/upb/bindings/lua/upb/table.c
@@ -162,7 +162,7 @@ static const struct luaL_Reg lupbtable_toplevel_m[] = {
   {NULL, NULL}
 };
 
-int luaopen_upbtable(lua_State *L) {
+int luaopen_upb_table_c(lua_State *L) {
   static char module_key;
   if (lupb_openlib(L, &module_key, "upb.table", lupbtable_toplevel_m)) {
     return 1;
diff --git a/upb/bindings/lua/upb/table.lua b/upb/bindings/lua/upb/table.lua
new file mode 100644
index 0000000000..8a0a9c9698
--- /dev/null
+++ b/upb/bindings/lua/upb/table.lua
@@ -0,0 +1,11 @@
+--[[--------------------------------------------------------------------
+
+  upb - a minimalist implementation of protocol buffers.
+
+  Copyright (c) 2009 Google Inc.  See LICENSE for details.
+  Author: Josh Haberman <jhaberman@gmail.com>
+
+--------------------------------------------------------------------]]--
+
+require "upb"
+return require "upb.table_c"