diff --git a/src/streams.h b/src/streams.h
--- a/src/streams.h
+++ b/src/streams.h
@@ -470,6 +470,99 @@
     }
 };
 
+template <typename IStream> class BitStreamReader {
+private:
+    IStream &m_istream;
+
+    /// Buffered byte read in from the input stream. A new byte is read into the
+    /// buffer when m_offset reaches 8.
+    uint8_t m_buffer{0};
+
+    /// Number of high order bits in m_buffer already returned by previous
+    /// Read() calls. The next bit to be returned is at this offset from the
+    /// most significant bit position.
+    int m_offset{8};
+
+public:
+    explicit BitStreamReader(IStream &istream) : m_istream(istream) {}
+
+    /** Read the specified number of bits from the stream. The data is returned
+     * in the nbits least signficant bits of a 64-bit uint.
+     */
+    uint64_t Read(int nbits) {
+        if (nbits < 0 || nbits > 64) {
+            throw std::out_of_range("nbits must be between 0 and 64");
+        }
+
+        uint64_t data = 0;
+        while (nbits > 0) {
+            if (m_offset == 8) {
+                m_istream >> m_buffer;
+                m_offset = 0;
+            }
+
+            int bits = std::min(8 - m_offset, nbits);
+            data <<= bits;
+            data |= static_cast<uint8_t>(m_buffer << m_offset) >> (8 - bits);
+            m_offset += bits;
+            nbits -= bits;
+        }
+        return data;
+    }
+};
+
+template <typename OStream> class BitStreamWriter {
+private:
+    OStream &m_ostream;
+
+    /// Buffered byte waiting to be written to the output stream. The byte is
+    /// written buffer when m_offset reaches 8 or Flush() is called.
+    uint8_t m_buffer{0};
+
+    /// Number of high order bits in m_buffer already written by previous
+    /// Write() calls and not yet flushed to the stream. The next bit to be
+    /// written to is at this offset from the most significant bit position.
+    int m_offset{0};
+
+public:
+    explicit BitStreamWriter(OStream &ostream) : m_ostream(ostream) {}
+
+    ~BitStreamWriter() { Flush(); }
+
+    /** Write the nbits least significant bits of a 64-bit int to the output
+     * stream. Data is buffered until it completes an octet.
+     */
+    void Write(uint64_t data, int nbits) {
+        if (nbits < 0 || nbits > 64) {
+            throw std::out_of_range("nbits must be between 0 and 64");
+        }
+
+        while (nbits > 0) {
+            int bits = std::min(8 - m_offset, nbits);
+            m_buffer |= (data << (64 - nbits)) >> (64 - 8 + m_offset);
+            m_offset += bits;
+            nbits -= bits;
+
+            if (m_offset == 8) {
+                Flush();
+            }
+        }
+    }
+
+    /** Flush any unwritten bits to the output stream, padding with 0's to the
+     * next byte boundary.
+     */
+    void Flush() {
+        if (m_offset == 0) {
+            return;
+        }
+
+        m_ostream << m_buffer;
+        m_buffer = 0;
+        m_offset = 0;
+    }
+};
+
 /**
  * Non-refcounted RAII wrapper for FILE*
  *
diff --git a/src/test/streams_tests.cpp b/src/test/streams_tests.cpp
--- a/src/test/streams_tests.cpp
+++ b/src/test/streams_tests.cpp
@@ -116,6 +116,42 @@
     BOOST_CHECK_THROW(reader >> d, std::ios_base::failure);
 }
 
+BOOST_AUTO_TEST_CASE(bitstream_reader_writer) {
+    CDataStream data(SER_NETWORK, INIT_PROTO_VERSION);
+
+    BitStreamWriter<CDataStream> bit_writer(data);
+    bit_writer.Write(0, 1);
+    bit_writer.Write(2, 2);
+    bit_writer.Write(6, 3);
+    bit_writer.Write(11, 4);
+    bit_writer.Write(1, 5);
+    bit_writer.Write(32, 6);
+    bit_writer.Write(7, 7);
+    bit_writer.Write(30497, 16);
+    bit_writer.Flush();
+
+    CDataStream data_copy(data);
+    uint32_t serialized_int1;
+    data >> serialized_int1;
+    BOOST_CHECK_EQUAL(serialized_int1,
+                      (uint32_t)0x7700C35A); // NOTE: Serialized as LE
+    uint16_t serialized_int2;
+    data >> serialized_int2;
+    BOOST_CHECK_EQUAL(serialized_int2,
+                      (uint16_t)0x1072); // NOTE: Serialized as LE
+
+    BitStreamReader<CDataStream> bit_reader(data_copy);
+    BOOST_CHECK_EQUAL(bit_reader.Read(1), 0);
+    BOOST_CHECK_EQUAL(bit_reader.Read(2), 2);
+    BOOST_CHECK_EQUAL(bit_reader.Read(3), 6);
+    BOOST_CHECK_EQUAL(bit_reader.Read(4), 11);
+    BOOST_CHECK_EQUAL(bit_reader.Read(5), 1);
+    BOOST_CHECK_EQUAL(bit_reader.Read(6), 32);
+    BOOST_CHECK_EQUAL(bit_reader.Read(7), 7);
+    BOOST_CHECK_EQUAL(bit_reader.Read(16), 30497);
+    BOOST_CHECK_THROW(bit_reader.Read(8), std::ios_base::failure);
+}
+
 BOOST_AUTO_TEST_CASE(streams_serializedata_xor) {
     std::vector<char> in;
     std::vector<char> expected_xor;