diff --git a/aliBuild b/aliBuild
index ce014fb1..11be05fc 100755
--- a/aliBuild
+++ b/aliBuild
@@ -60,7 +60,7 @@ def doMain(args, parser):
 
   if args.action == "version":
     print("aliBuild version: {version} ({arch})".format(
-      version=__version__, arch=args.architecture or "unknown"))
+      version=__version__ or "unknown", arch=args.architecture or "unknown"))
     sys.exit(0)
 
   if args.action == "doctor":
@@ -91,7 +91,7 @@ if __name__ == "__main__":
   logger.setLevel(logging.DEBUG if args.debug else logging.INFO)
 
   os.environ["ALIBUILD_ANALYTICS_ID"] = "UA-77346950-1"
-  os.environ["ALIBUILD_VERSION"] = __version__
+  os.environ["ALIBUILD_VERSION"] = __version__ or ""
   if args.action == "analytics":
     if args.state == "off":
       disable_analytics()
diff --git a/alibuild_helpers/__init__.py b/alibuild_helpers/__init__.py
index 1d511a49..0692cfb5 100644
--- a/alibuild_helpers/__init__.py
+++ b/alibuild_helpers/__init__.py
@@ -9,13 +9,13 @@
     try:
         from setuptools_scm import get_version
     except ImportError:
-        __version__ = '(could not detect version)'
+        __version__ = None
     else:
         import os.path
         source_root = os.path.join(os.path.dirname(__file__), os.path.pardir)
         try:
             __version__ = get_version(root=source_root)
         except LookupError:
-            __version__ = '(could not detect version)'
+            __version__ = None
         finally:
             del get_version, source_root
diff --git a/alibuild_helpers/args.py b/alibuild_helpers/args.py
index 651a2ca1..d226c070 100644
--- a/alibuild_helpers/args.py
+++ b/alibuild_helpers/args.py
@@ -105,6 +105,12 @@ def doParseArgs():
                                   "same effect as adding 'force_rebuild: true' to its recipe "
                                   "in CONFIGDIR. You can specify this option multiple times or "
                                   "separate multiple arguments with commas."))
+  build_parser.add_argument("--annotate", default=[], action="append", metavar="PACKAGE=COMMENT",
+                            help=("Store COMMENT in the build metadata for PACKAGE. This option "
+                                  "can be given multiple times, if you want to store comments "
+                                  "in multiple packages. The comment will only be stored if "
+                                  "PACKAGE is compiled or downloaded during this run; if it "
+                                  "already exists, this does not happen."))
 
   build_docker = build_parser.add_argument_group(title="Build inside a container", description="""\
   Builds can be done inside a Docker container, to make it easier to get a
@@ -434,6 +440,16 @@ def finaliseArgs(args, parser):
     if args.docker and not args.dockerImage:
       args.dockerImage = "registry.cern.ch/alisw/%s-builder" % args.architecture.split("_")[0]
 
+  if "annotate" in args:
+    for comment_assignment in args.annotate:
+      if "=" not in comment_assignment:
+        parser.error("--annotate takes arguments of the form PACKAGE=COMMENT")
+    args.annotate = {
+      package: comment
+      for package, _, comment
+      in (assignment.partition("=") for assignment in args.annotate)
+    }
+
   if args.action in ("build", "doctor"):
     args.configDir = args.configDir
 
diff --git a/alibuild_helpers/build.py b/alibuild_helpers/build.py
index 2da9aa84..3b59460e 100644
--- a/alibuild_helpers/build.py
+++ b/alibuild_helpers/build.py
@@ -431,6 +431,44 @@ def generate_initdotsh(package, specs, architecture, post_build=False):
   return "\n".join(lines)
 
 
+def create_provenance_info(package, specs, args):
+  """Return a metadata record for storage in the package's install directory."""
+
+  def spec_info(spec):
+    return {
+      "name": spec["package"],
+      "tag": spec.get("tag"),
+      "source": spec.get("source"),
+      "version": spec["version"],
+      "revision": spec["revision"],
+      "hash": spec["hash"],
+    }
+
+  def dependency_list(key):
+    return [spec_info(specs[dep]) for dep in specs[package].get(key, ())]
+
+  return json.dumps({
+    "comment": args.annotate.get(package),
+    "alibuild_version": __version__,
+    "alidist": {
+      "commit": os.environ["ALIBUILD_ALIDIST_HASH"],
+    },
+    "architecture": args.architecture,
+    "defaults": args.defaults,
+    "package": spec_info(specs[package]),
+    "dependencies": {
+      "direct": {
+        "build": dependency_list("build_requires"),
+        "runtime": dependency_list("runtime_requires"),
+      },
+      "recursive": {  # includes direct deps and deps' deps
+        "build": dependency_list("full_build_requires"),
+        "runtime": dependency_list("full_runtime_requires"),
+      },
+    },
+  })
+
+
 def doBuild(args, parser):
   if args.remoteStore.startswith("http"):
     syncHelper = HttpRemoteSync(args.remoteStore, args.architecture, args.workDir, args.insecure)
@@ -491,7 +529,7 @@ def doBuild(args, parser):
   debug("Building for architecture %s", args.architecture)
   debug("Number of parallel builds: %d", args.jobs)
   debug("Using aliBuild from alibuild@%s recipes in alidist@%s",
-        __version__, os.environ["ALIBUILD_ALIDIST_HASH"])
+        __version__ or "unknown", os.environ["ALIBUILD_ALIDIST_HASH"])
 
   install_wrapper_script("git", workDir)
 
@@ -1071,13 +1109,7 @@ def doBuild(args, parser):
     dieOnError(err, "Failed to create script dir %s: %s" % (scriptDir, out))
     writeAll("%s/%s.sh" % (scriptDir, spec["package"]), spec["recipe"])
     writeAll("%s/build.sh" % scriptDir, cmd_raw % {
-      "dependenciesJSON": json.dumps({dep: {
-        "architecture": args.architecture,
-        "package": dep,
-        "version": specs[dep]["version"],
-        "revision": specs[dep]["revision"],
-        "hash": specs[dep]["hash"],
-      } for dep in spec.get("full_requires", ())}),
+      "provenance": create_provenance_info(spec["package"], specs, args),
       "initdotsh_deps": generate_initdotsh(p, specs, args.architecture, post_build=False),
       "initdotsh_full": generate_initdotsh(p, specs, args.architecture, post_build=True),
       "develPrefix": develPrefix,
diff --git a/alibuild_helpers/build_template.sh b/alibuild_helpers/build_template.sh
index 9ef0d3d7..06363df9 100644
--- a/alibuild_helpers/build_template.sh
+++ b/alibuild_helpers/build_template.sh
@@ -77,8 +77,8 @@ fi
 mkdir -p "$INSTALLROOT" "$BUILDROOT" "$BUILDDIR" "$WORK_DIR/INSTALLROOT/$PKGHASH/$PKGPATH"
 
 cd "$WORK_DIR/INSTALLROOT/$PKGHASH"
-cat <<\EOF > "$INSTALLROOT/.full-dependencies"
-%(dependenciesJSON)s
+cat > "$INSTALLROOT/.meta.json" <<\EOF
+%(provenance)s
 EOF
 
 # Add "source" command for dependencies to init.sh.
@@ -207,8 +207,8 @@ source_up
 unset DYLD_LIBRARY_PATH
 EOF
 
-cat <<\EOF > "$INSTALLROOT/.full-dependencies"
-%(dependenciesJSON)s
+cat > "$INSTALLROOT/.meta.json" <<\EOF
+%(provenance)s
 EOF
 
 cd "$WORK_DIR/INSTALLROOT/$PKGHASH/$PKGPATH"
diff --git a/tests/test_args.py b/tests/test_args.py
index 7e0c0ea0..3d07562b 100644
--- a/tests/test_args.py
+++ b/tests/test_args.py
@@ -34,6 +34,7 @@
   "build zlib --architecture foo": ARCHITECTURE_ERROR,
   "build --force-unknown-architecture zlib --remote-store rsync://test1.local/::rw --write-store rsync://test2.local/::rw ": [call('cannot specify ::rw and --write-store at the same time')],
   "build zlib -a osx_x86-64 --docker-image foo": [call('cannot use `-a osx_x86-64` and --docker')],
+  "build zlib -a slc7_x86-64 --annotate foobar": [call("--annotate takes arguments of the form PACKAGE=COMMENT")],
   "analytics": [call(ANALYTICS_MISSING_STATE_ERROR)]
 }
 
diff --git a/tests/test_build.py b/tests/test_build.py
index 821dd180..0532a38e 100644
--- a/tests/test_build.py
+++ b/tests/test_build.py
@@ -264,6 +264,7 @@ def test_coverDoBuild(self, mock_debug, mock_listdir, mock_warning, mock_sys, mo
             force_rebuild=[],
             defaults="release",
             jobs=2,
+            annotate={},
             preferSystem=[],
             noSystem=False,
             debug=True,