diff --git a/objectivec/BUILD.bazel b/objectivec/BUILD.bazel
index 3a63685b2f..fae65c298f 100644
--- a/objectivec/BUILD.bazel
+++ b/objectivec/BUILD.bazel
@@ -1,6 +1,60 @@
 load("@rules_cc//cc:defs.bzl", "objc_library")
 load("@rules_pkg//:mappings.bzl", "pkg_files", "strip_prefix")
+load("@upb//cmake:build_defs.bzl", "staleness_test")
 load("//conformance:defs.bzl", "conformance_test")
+load(":defs.bzl", "objc_proto_camel_case_name")
+
+# The WKTs have to be checked in to support the CocoaPods and Xcode builds. This
+# generule and test ensure the source are current.
+#
+# TODO: Improve the bazel build so it uses these generated headers so it is
+# always current, and only the builds that can't easily build protoc and
+# generate the files rely on the checked in ones.
+
+_WELL_KNOWN_TYPES = [
+    "any",
+    "api",
+    "duration",
+    "empty",
+    "field_mask",
+    "source_context",
+    "struct",
+    "timestamp",
+    "type",
+    "wrappers",
+]
+
+_OBJC_WKT_NAMES = [objc_proto_camel_case_name(x) for x in _WELL_KNOWN_TYPES]
+
+_OBJC_EXTS = [
+    ".pbobjc.h",
+    ".pbobjc.m",
+]
+
+genrule(
+    name = "gen_wkt_sources",
+    srcs = ["//src/google/protobuf:well_known_type_protos"],
+    outs = ["wkt/GPB" + wkt + ext for wkt in _OBJC_WKT_NAMES for ext in _OBJC_EXTS],
+    cmd = " && ".join([
+        "$(execpath //:protoc) --objc_out=$(RULEDIR)/wkt --proto_path=src $(SRCS)",
+    ] + [
+        "mv $(RULEDIR)/wkt/google/protobuf/" + wkt + ext + " $(RULEDIR)/wkt/GPB" + wkt + ext
+        for wkt in _OBJC_WKT_NAMES
+        for ext in _OBJC_EXTS
+    ]),
+    exec_tools = ["//:protoc"],
+)
+
+staleness_test(
+    name = "well_known_types_staleness_test",
+    outs = ["GPB" + wkt + ext for wkt in _OBJC_WKT_NAMES for ext in _OBJC_EXTS],
+    generated_pattern = "wkt/%s",
+    tags = ["manual"],
+)
+
+################################################################################
+# Objective-C Runtime Library
+################################################################################
 
 objc_library(
     name = "objectivec",
diff --git a/objectivec/defs.bzl b/objectivec/defs.bzl
new file mode 100644
index 0000000000..5535868bd7
--- /dev/null
+++ b/objectivec/defs.bzl
@@ -0,0 +1,68 @@
+"""Starlark helpers for Objective-C protos."""
+
+# State constants for objc_proto_camel_case_name.
+_last_was_other = 0
+_last_was_lowercase = 1
+_last_was_uppercase = 2
+_last_was_number = 3
+
+def objc_proto_camel_case_name(name):
+    """A Starlark version of the ObjC generator's CamelCase name transform.
+
+    This needs to track
+    src/google/protobuf/compiler/objectivec/names.cc's UnderscoresToCamelCase()
+
+    NOTE: This code is written to model the C++ in protoc's ObjC generator so it
+    is easier to confirm that the algorithms between the implementations match.
+    The customizations for starlark performance are:
+    - The cascade within the loop is reordered and special cases "_" to
+      optimize for google3 inputs.
+    - The "last was" state is handled via integers instead of three booleans.
+
+    The `first_capitalized` argument in the C++ code is left off this code and
+    it acts as if the value were `True`.
+
+    Args:
+      name: The proto file name to convert to camel case. The extension should
+        already be removed.
+
+    Returns:
+      The converted proto name to camel case.
+    """
+    segments = []
+    current = ""
+    last_was = _last_was_other
+    for c in name.elems():
+        if c.islower():
+            # lowercase letter can follow a lowercase or uppercase letter.
+            if last_was != _last_was_lowercase and last_was != _last_was_uppercase:
+                segments.append(current)
+                current = c.upper()
+            else:
+                current += c
+            last_was = _last_was_lowercase
+        elif c == "_":  # more common than rest, special case it.
+            last_was = _last_was_other
+        elif c.isdigit():
+            if last_was != _last_was_number:
+                segments.append(current)
+                current = ""
+            current += c
+            last_was = _last_was_number
+        elif c.isupper():
+            if last_was != _last_was_uppercase:
+                segments.append(current)
+                current = c
+            else:
+                current += c.lower()
+            last_was = _last_was_uppercase
+        else:
+            last_was = _last_was_other
+    segments.append(current)
+    result = ""
+    for x in segments:
+        if x in ("Url", "Http", "Https"):
+            result += x.upper()
+        else:
+            result += x
+    return result
diff --git a/regenerate_stale_files.sh b/regenerate_stale_files.sh
index 1c38104135..58c640b38b 100755
--- a/regenerate_stale_files.sh
+++ b/regenerate_stale_files.sh
@@ -15,6 +15,7 @@ readonly BazelBin="${BAZEL:-bazel} ${BAZEL_STARTUP_FLAGS}"
 # Run and fix all staleness tests.
 ${BazelBin} test src:cmake_lists_staleness_test "$@" || ./bazel-bin/src/cmake_lists_staleness_test --fix
 ${BazelBin} test src/google/protobuf:well_known_types_staleness_test "$@" || ./bazel-bin/src/google/protobuf/well_known_types_staleness_test --fix
+${BazelBin} test objectivec:well_known_types_staleness_test "$@" || ./bazel-bin/objectivec/well_known_types_staleness_test --fix
 
 # Generate C# code.
 # This doesn't currently have Bazel staleness tests, but there's an existing