diff --git a/.gitmodules b/.gitmodules
index faad88a857..ef87dd1ba1 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -29,3 +29,6 @@
 [submodule "frozen/Adafruit_CircuitPython_BusDevice"]
 	path = frozen/Adafruit_CircuitPython_BusDevice
 	url = https://github.com/adafruit/Adafruit_CircuitPython_BusDevice.git
+[submodule "tools/python-semver"]
+	path = tools/python-semver
+	url = https://github.com/k-bx/python-semver.git
diff --git a/py/mkenv.mk b/py/mkenv.mk
index 5a118854aa..5f8cd902bf 100644
--- a/py/mkenv.mk
+++ b/py/mkenv.mk
@@ -70,6 +70,7 @@ endif
 MAKE_FROZEN = $(TOP)/tools/make-frozen.py
 MPY_CROSS = $(TOP)/mpy-cross/mpy-cross
 MPY_TOOL = $(TOP)/tools/mpy-tool.py
+PREPROCESS_FROZEN_MODULES = PYTHONPATH=$(TOP)/tools/python-semver $(TOP)/tools/preprocess_frozen_modules.py
 
 all:
 .PHONY: all
diff --git a/py/mkrules.mk b/py/mkrules.mk
index 1b33555128..713e69c622 100644
--- a/py/mkrules.mk
+++ b/py/mkrules.mk
@@ -114,14 +114,13 @@ $(MPY_CROSS): $(TOP)/py/*.[ch] $(TOP)/mpy-cross/*.[ch] $(TOP)/windows/fmode.c
 	$(Q)$(MAKE) -C $(TOP)/mpy-cross
 
 # Copy all the modules and single python files to freeze to a common area, omitting top-level dirs (the repo names).
-# Remove any conf.py (sphinx config) and setup.py (module install info) files, which are not meant to be frozen.
-# Also remove the library examples directory, so it won't be included.
+# Do any preprocessing necessary: currently, this adds version information, removes examples, and
+# non-library .py files in the modules (setup.py and conf.py)
 # Then compile .mpy files from all the .py files, placing them in the same directories as the .py files.
 $(BUILD)/frozen_mpy: $(FROZEN_MPY_DIRS)
 	$(ECHO) FREEZE $(FROZEN_MPY_DIRS)
 	$(Q)$(MKDIR) -p $@
-	$(Q)$(RSYNC) -rL --include="*/" --include='*.py' --exclude="*" $(addsuffix /*,$(FROZEN_MPY_DIRS)) $@
-	$(Q)$(RM) -rf $@/conf.py $@/setup.py $@/examples
+	$(Q)$(PREPROCESS_FROZEN_MODULES) -o $@ $(FROZEN_MPY_DIRS)
 	$(Q)$(CD) $@ && \
 $(FIND) -L . -type f -name '*.py' | sed 's=^\./==' | \
 xargs -n1 $(abspath $(MPY_CROSS)) $(MPY_CROSS_FLAGS)
diff --git a/tools/preprocess_frozen_modules.py b/tools/preprocess_frozen_modules.py
new file mode 100755
index 0000000000..0233fba614
--- /dev/null
+++ b/tools/preprocess_frozen_modules.py
@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+import argparse
+import os
+import os.path
+from pathlib import Path
+import semver
+import subprocess
+
+# Compatible with Python 3.4 due to travis using trusty as default.
+
+def version_string(path=None, *, valid_semver=False):
+    version = None
+    try:
+        tag = subprocess.check_output('git describe --tags --exact-match', shell=True, cwd=path)
+        version = tag.strip().decode("utf-8", "strict")
+    except subprocess.CalledProcessError:
+        describe = subprocess.check_output("git describe --tags", shell=True, cwd=path)
+        tag, additional_commits, commitish = describe.strip().decode("utf-8", "strict").rsplit("-", maxsplit=2)
+        commitish = commitish[1:]
+        if valid_semver:
+            version_info = semver.parse_version_info(tag)
+            if not version_info.prerelease:
+                version = semver.bump_patch(tag) + "-alpha.0.plus." + additional_commits + "+" + commitish
+            else:
+                version = tag + ".plus." + additional_commits + "+" + commitish
+        else:
+            version = commitish
+    return version
+
+# Visit all the .py files in topdir. Replace any __version__ = "0.0.0-auto.0" type of info
+# with actual version info derived from git.
+def copy_and_process(in_dir, out_dir):
+    for root, subdirs, files in os.walk(in_dir):
+
+        # Skip library examples directories.
+        if Path(root).name == 'examples':
+            continue
+
+        for file in files:
+            # Skip top-level setup.py (module install info) and conf.py (sphinx config),
+            # which are not part of the library
+            if (root == in_dir) and file in ('conf.py', 'setup.py'):
+                continue
+
+            input_file_path = Path(root, file)
+            output_file_path = Path(out_dir, input_file_path.relative_to(in_dir))
+
+            if file.endswith(".py"):
+                if not output_file_path.parent.exists():
+                    output_file_path.parent.mkdir(parents=True)
+                with input_file_path.open("r") as input, output_file_path.open("w") as output:
+                    for line in input:
+                        if line.startswith("__version__"):
+                            module_version = version_string(root, valid_semver=True)
+                            line = line.replace("0.0.0-auto.0", module_version)
+                        output.write(line)
+
+if __name__ == '__main__':
+    argparser = argparse.ArgumentParser(description="""\
+    Copy and pre-process .py files into output directory, before freezing.
+    1. Remove top-level repo directory.
+    2. Update __version__ info.
+    3. Remove examples.
+    4. Remove non-library setup.py and conf.py""")
+    argparser.add_argument("in_dirs", metavar="input-dir", nargs="+",
+                           help="top-level code dirs (may be git repo dirs)")
+    argparser.add_argument("-o", "--out_dir", help="output directory")
+    args = argparser.parse_args()
+
+    for in_dir in args.in_dirs:
+        copy_and_process(in_dir, args.out_dir)
diff --git a/tools/python-semver b/tools/python-semver
new file mode 160000
index 0000000000..2001c62d1a
--- /dev/null
+++ b/tools/python-semver
@@ -0,0 +1 @@
+Subproject commit 2001c62d1a0361c44acc7076d8ce91e1d1c66141