--- a/include/llvm/Support/Endian.h	Wed Feb 18 14:56:07 2015 +0900
+++ b/include/llvm/Support/Endian.h	Tue Oct 13 17:48:58 2015 +0900
@@ -58,8 +58,9 @@
 
 /// Read a value of a particular endianness from a buffer, and increment the
 /// buffer past that value.
-template<typename value_type, endianness endian, std::size_t alignment>
-inline value_type readNext(const unsigned char *&memory) {
+template<typename value_type, endianness endian, std::size_t alignment,
+         typename CharT>
+inline value_type readNext(const CharT *&memory) {
   value_type ret = read<value_type, endian, alignment>(memory);
   memory += sizeof(value_type);
   return ret;
@@ -76,6 +77,95 @@
          &value,
          sizeof(value_type));
 }
+
+template <typename value_type>
+using make_unsigned_t = typename std::make_unsigned<value_type>::type;
+
+/// Read a value of a particular endianness from memory, for a location
+/// that starts at the given bit offset within the first byte.
+template <typename value_type, endianness endian, std::size_t alignment>
+inline value_type readAtBitAlignment(const void *memory, uint64_t startBit) {
+  assert(startBit < 8);
+  if (startBit == 0)
+    return read<value_type, endian, alignment>(memory);
+  else {
+    // Read two values and compose the result from them.
+    value_type val[2];
+    memcpy(&val[0],
+           LLVM_ASSUME_ALIGNED(
+               memory, (detail::PickAlignment<value_type, alignment>::value)),
+           sizeof(value_type) * 2);
+    val[0] = byte_swap<value_type, endian>(val[0]);
+    val[1] = byte_swap<value_type, endian>(val[1]);
+
+    // Shift bits from the lower value into place.
+    make_unsigned_t<value_type> lowerVal = val[0] >> startBit;
+    // Mask off upper bits after right shift in case of signed type.
+    make_unsigned_t<value_type> numBitsFirstVal =
+        (sizeof(value_type) * 8) - startBit;
+    lowerVal &= ((make_unsigned_t<value_type>)1 << numBitsFirstVal) - 1;
+
+    // Get the bits from the upper value.
+    make_unsigned_t<value_type> upperVal =
+        val[1] & (((make_unsigned_t<value_type>)1 << startBit) - 1);
+    // Shift them in to place.
+    upperVal <<= numBitsFirstVal;
+
+    return lowerVal | upperVal;
+  }
+}
+
+/// Write a value to memory with a particular endianness, for a location
+/// that starts at the given bit offset within the first byte.
+template <typename value_type, endianness endian, std::size_t alignment>
+inline void writeAtBitAlignment(void *memory, value_type value,
+                                uint64_t startBit) {
+  assert(startBit < 8);
+  if (startBit == 0)
+    write<value_type, endian, alignment>(memory, value);
+  else {
+    // Read two values and shift the result into them.
+    value_type val[2];
+    memcpy(&val[0],
+           LLVM_ASSUME_ALIGNED(
+               memory, (detail::PickAlignment<value_type, alignment>::value)),
+           sizeof(value_type) * 2);
+    val[0] = byte_swap<value_type, endian>(val[0]);
+    val[1] = byte_swap<value_type, endian>(val[1]);
+
+    // Mask off any existing bits in the upper part of the lower value that
+    // we want to replace.
+    val[0] &= ((make_unsigned_t<value_type>)1 << startBit) - 1;
+    make_unsigned_t<value_type> numBitsFirstVal =
+        (sizeof(value_type) * 8) - startBit;
+    make_unsigned_t<value_type> lowerVal = value;
+    if (startBit > 0) {
+      // Mask off the upper bits in the new value that are not going to go into
+      // the lower value. This avoids a left shift of a negative value, which
+      // is undefined behavior.
+      lowerVal &= (((make_unsigned_t<value_type>)1 << numBitsFirstVal) - 1);
+      // Now shift the new bits into place
+      lowerVal <<= startBit;
+    }
+    val[0] |= lowerVal;
+
+    // Mask off any existing bits in the lower part of the upper value that
+    // we want to replace.
+    val[1] &= ~(((make_unsigned_t<value_type>)1 << startBit) - 1);
+    // Next shift the bits that go into the upper value into position.
+    make_unsigned_t<value_type> upperVal = value >> numBitsFirstVal;
+    // Mask off upper bits after right shift in case of signed type.
+    upperVal &= ((make_unsigned_t<value_type>)1 << startBit) - 1;
+    val[1] |= upperVal;
+
+    // Finally, rewrite values.
+    val[0] = byte_swap<value_type, endian>(val[0]);
+    val[1] = byte_swap<value_type, endian>(val[1]);
+    memcpy(LLVM_ASSUME_ALIGNED(
+               memory, (detail::PickAlignment<value_type, alignment>::value)),
+           &val[0], sizeof(value_type) * 2);
+  }
+}
 } // end namespace endian
 
 namespace detail {
@@ -103,6 +193,16 @@
     return *this;
   }
 
+  packed_endian_specific_integral &operator|=(value_type newValue) {
+    *this = *this | newValue;
+    return *this;
+  }
+
+  packed_endian_specific_integral &operator&=(value_type newValue) {
+    *this = *this & newValue;
+    return *this;
+  }
+
 private:
   AlignedCharArray<PickAlignment<value_type, alignment>::value,
                    sizeof(value_type)> Value;
@@ -195,7 +295,23 @@
                    <int32_t, native, unaligned> unaligned_int32_t;
 typedef detail::packed_endian_specific_integral
                    <int64_t, native, unaligned> unaligned_int64_t;
+
+namespace endian {
+inline uint16_t read16le(const void *p) { return *(const ulittle16_t *)p; }
+inline uint32_t read32le(const void *p) { return *(const ulittle32_t *)p; }
+inline uint64_t read64le(const void *p) { return *(const ulittle64_t *)p; }
+inline uint16_t read16be(const void *p) { return *(const ubig16_t *)p; }
+inline uint32_t read32be(const void *p) { return *(const ubig32_t *)p; }
+inline uint64_t read64be(const void *p) { return *(const ubig64_t *)p; }
+
+inline void write16le(void *p, uint16_t v) { *(ulittle16_t *)p = v; }
+inline void write32le(void *p, uint32_t v) { *(ulittle32_t *)p = v; }
+inline void write64le(void *p, uint64_t v) { *(ulittle64_t *)p = v; }
+inline void write16be(void *p, uint16_t v) { *(ubig16_t *)p = v; }
+inline void write32be(void *p, uint32_t v) { *(ubig32_t *)p = v; }
+inline void write64be(void *p, uint64_t v) { *(ubig64_t *)p = v; }
+} // end namespace endian
+} // end namespace support
 } // end namespace llvm
-} // end namespace support
 
 #endif