diff --git a/objectivec/GPBCodedOutputStream_PackagePrivate.h b/objectivec/GPBCodedOutputStream_PackagePrivate.h
new file mode 100644
index 0000000..2e7bb4c
--- /dev/null
+++ b/objectivec/GPBCodedOutputStream_PackagePrivate.h
@@ -0,0 +1,126 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#import "GPBCodedOutputStream.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+CF_EXTERN_C_BEGIN
+
+size_t GPBComputeDoubleSize(int32_t fieldNumber, double value)
+    __attribute__((const));
+size_t GPBComputeFloatSize(int32_t fieldNumber, float value)
+    __attribute__((const));
+size_t GPBComputeUInt64Size(int32_t fieldNumber, uint64_t value)
+    __attribute__((const));
+size_t GPBComputeInt64Size(int32_t fieldNumber, int64_t value)
+    __attribute__((const));
+size_t GPBComputeInt32Size(int32_t fieldNumber, int32_t value)
+    __attribute__((const));
+size_t GPBComputeFixed64Size(int32_t fieldNumber, uint64_t value)
+    __attribute__((const));
+size_t GPBComputeFixed32Size(int32_t fieldNumber, uint32_t value)
+    __attribute__((const));
+size_t GPBComputeBoolSize(int32_t fieldNumber, BOOL value)
+    __attribute__((const));
+size_t GPBComputeStringSize(int32_t fieldNumber, NSString *value)
+    __attribute__((const));
+size_t GPBComputeGroupSize(int32_t fieldNumber, GPBMessage *value)
+    __attribute__((const));
+size_t GPBComputeUnknownGroupSize(int32_t fieldNumber,
+                                  GPBUnknownFieldSet *value)
+    __attribute__((const));
+size_t GPBComputeMessageSize(int32_t fieldNumber, GPBMessage *value)
+    __attribute__((const));
+size_t GPBComputeBytesSize(int32_t fieldNumber, NSData *value)
+    __attribute__((const));
+size_t GPBComputeUInt32Size(int32_t fieldNumber, uint32_t value)
+    __attribute__((const));
+size_t GPBComputeSFixed32Size(int32_t fieldNumber, int32_t value)
+    __attribute__((const));
+size_t GPBComputeSFixed64Size(int32_t fieldNumber, int64_t value)
+    __attribute__((const));
+size_t GPBComputeSInt32Size(int32_t fieldNumber, int32_t value)
+    __attribute__((const));
+size_t GPBComputeSInt64Size(int32_t fieldNumber, int64_t value)
+    __attribute__((const));
+size_t GPBComputeTagSize(int32_t fieldNumber) __attribute__((const));
+size_t GPBComputeWireFormatTagSize(int field_number, GPBDataType dataType)
+    __attribute__((const));
+
+size_t GPBComputeDoubleSizeNoTag(double value) __attribute__((const));
+size_t GPBComputeFloatSizeNoTag(float value) __attribute__((const));
+size_t GPBComputeUInt64SizeNoTag(uint64_t value) __attribute__((const));
+size_t GPBComputeInt64SizeNoTag(int64_t value) __attribute__((const));
+size_t GPBComputeInt32SizeNoTag(int32_t value) __attribute__((const));
+size_t GPBComputeFixed64SizeNoTag(uint64_t value) __attribute__((const));
+size_t GPBComputeFixed32SizeNoTag(uint32_t value) __attribute__((const));
+size_t GPBComputeBoolSizeNoTag(BOOL value) __attribute__((const));
+size_t GPBComputeStringSizeNoTag(NSString *value) __attribute__((const));
+size_t GPBComputeGroupSizeNoTag(GPBMessage *value) __attribute__((const));
+size_t GPBComputeUnknownGroupSizeNoTag(GPBUnknownFieldSet *value)
+    __attribute__((const));
+size_t GPBComputeMessageSizeNoTag(GPBMessage *value) __attribute__((const));
+size_t GPBComputeBytesSizeNoTag(NSData *value) __attribute__((const));
+size_t GPBComputeUInt32SizeNoTag(int32_t value) __attribute__((const));
+size_t GPBComputeEnumSizeNoTag(int32_t value) __attribute__((const));
+size_t GPBComputeSFixed32SizeNoTag(int32_t value) __attribute__((const));
+size_t GPBComputeSFixed64SizeNoTag(int64_t value) __attribute__((const));
+size_t GPBComputeSInt32SizeNoTag(int32_t value) __attribute__((const));
+size_t GPBComputeSInt64SizeNoTag(int64_t value) __attribute__((const));
+
+// Note that this will calculate the size of 64 bit values truncated to 32.
+size_t GPBComputeSizeTSizeAsInt32NoTag(size_t value) __attribute__((const));
+
+size_t GPBComputeRawVarint32Size(int32_t value) __attribute__((const));
+size_t GPBComputeRawVarint64Size(int64_t value) __attribute__((const));
+
+// Note that this will calculate the size of 64 bit values truncated to 32.
+size_t GPBComputeRawVarint32SizeForInteger(NSInteger value)
+    __attribute__((const));
+
+// Compute the number of bytes that would be needed to encode a
+// MessageSet extension to the stream.  For historical reasons,
+// the wire format differs from normal fields.
+size_t GPBComputeMessageSetExtensionSize(int32_t fieldNumber, GPBMessage *value)
+    __attribute__((const));
+
+// Compute the number of bytes that would be needed to encode an
+// unparsed MessageSet extension field to the stream.  For
+// historical reasons, the wire format differs from normal fields.
+size_t GPBComputeRawMessageSetExtensionSize(int32_t fieldNumber, NSData *value)
+    __attribute__((const));
+
+size_t GPBComputeEnumSize(int32_t fieldNumber, int32_t value)
+    __attribute__((const));
+
+CF_EXTERN_C_END
+
+NS_ASSUME_NONNULL_END