Index: include/llvm/Support/SHA1.h
===================================================================
--- /dev/null
+++ include/llvm/Support/SHA1.h
@@ -0,0 +1,64 @@
+//==- SHA1.h - SHA1 implementation for LLVM                     --*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// This code is taken from public domain
+// (http://oauth.googlecode.com/svn/code/c/liboauth/src/sha1.c)
+// and modified by wrapping it in a C++ interface for LLVM,
+// and removing unnecessary code.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_SHA1_H
+#define LLVM_SUPPORT_SHA1_H
+
+#include "llvm/ADT/StringRef.h"
+
+#include <cstdint>
+
+namespace llvm {
+
+/// A class that wrap the SHA1 algorithm.
+class SHA1 {
+public:
+  SHA1() { init(); }
+
+  /// Reinitialize the internal state
+  void init();
+
+  /// Digest more data.
+  void write(const char *data, size_t len);
+
+  /// Return a reference to the current SHA1 for the digested data since the
+  /// last call to init()
+  StringRef result();
+
+private:
+  static constexpr int BLOCK_LENGTH = 64;
+  static constexpr int HASH_LENGTH = 20;
+
+  // Internal State
+  struct {
+    uint32_t Buffer[BLOCK_LENGTH / 4];
+    uint32_t State[HASH_LENGTH / 4];
+    uint32_t ByteCount;
+    uint8_t BufferOffset;
+  } InternalState;
+
+  // Internal copy of the hash, populated and accessed on calls to result()
+  uint32_t HashResult[HASH_LENGTH / 4];
+
+  // Helper
+  void writebyte(uint8_t data);
+  void hashBlock();
+  void addUncounted(uint8_t data);
+  void pad();
+};
+
+} // end llvm namespace
+
+#endif
Index: include/llvm/Support/raw_sha1_ostream.h
===================================================================
--- /dev/null
+++ include/llvm/Support/raw_sha1_ostream.h
@@ -0,0 +1,46 @@
+//==- raw_sha1_ostream.h - raw_ostream that compute SHA1        --*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the raw_sha1_ostream class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_RAW_SHA1_OSTREAM_H
+#define LLVM_SUPPORT_RAW_SHA1_OSTREAM_H
+
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/SHA1.h"
+
+namespace llvm {
+
+/// A raw_ostream that hash the content using the sha1 algorithm.
+class raw_sha1_ostream : public raw_ostream {
+  SHA1 State;
+
+  /// See raw_ostream::write_impl.
+  void write_impl(const char *Ptr, size_t Size) override {
+    State.write(Ptr, Size);
+  }
+
+public:
+  /// Return the current SHA1 hash for the content of the stream
+  StringRef sha1() {
+    flush();
+    return State.result();
+  }
+
+  /// Reset the internal state to start over from scratch.
+  void resetHash() { State.init(); }
+
+  uint64_t current_pos() const override { return 0; }
+};
+
+} // end llvm namespace
+
+#endif
Index: lib/Support/CMakeLists.txt
===================================================================
--- lib/Support/CMakeLists.txt
+++ lib/Support/CMakeLists.txt
@@ -76,6 +76,7 @@
   RandomNumberGenerator.cpp
   Regex.cpp
   ScaledNumber.cpp
+  SHA1.cpp
   SmallPtrSet.cpp
   SmallVector.cpp
   SourceMgr.cpp
Index: lib/Support/SHA1.cpp
===================================================================
--- /dev/null
+++ lib/Support/SHA1.cpp
@@ -0,0 +1,170 @@
+//======- SHA1.h - Private copy of the SHA1 implementation ---*- C++ -* ======//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// This code is taken from public domain
+// (http://oauth.googlecode.com/svn/code/c/liboauth/src/sha1.c)
+// and modified by wrapping it in a C++ interface for LLVM,
+// and removing unnecessary code.
+//
+//===----------------------------------------------------------------------===//
+
+/* This code is public-domain - it is based on libcrypt
+ * placed in the public domain by Wei Dai and other contributors.
+ */
+
+#include "llvm/Support/SHA1.h"
+using namespace llvm;
+
+#include <stdint.h>
+#include <string.h>
+
+#ifdef __BIG_ENDIAN__
+#define SHA_BIG_ENDIAN
+#elif defined __LITTLE_ENDIAN__
+/* override */
+#elif defined __BYTE_ORDER
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define SHA_BIG_ENDIAN
+#endif
+#else               // ! defined __LITTLE_ENDIAN__
+#include <endian.h> // machine/endian.h
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define SHA_BIG_ENDIAN
+#endif
+#endif
+
+/* code */
+#define SHA1_K0 0x5a827999
+#define SHA1_K20 0x6ed9eba1
+#define SHA1_K40 0x8f1bbcdc
+#define SHA1_K60 0xca62c1d6
+
+void SHA1::init() {
+  InternalState.State[0] = 0x67452301;
+  InternalState.State[1] = 0xefcdab89;
+  InternalState.State[2] = 0x98badcfe;
+  InternalState.State[3] = 0x10325476;
+  InternalState.State[4] = 0xc3d2e1f0;
+  InternalState.ByteCount = 0;
+  InternalState.BufferOffset = 0;
+}
+
+static uint32_t rol32(uint32_t number, uint8_t bits) {
+  return ((number << bits) | (number >> (32 - bits)));
+}
+
+void SHA1::hashBlock() {
+  uint8_t i;
+  uint32_t a, b, c, d, e, t;
+
+  a = InternalState.State[0];
+  b = InternalState.State[1];
+  c = InternalState.State[2];
+  d = InternalState.State[3];
+  e = InternalState.State[4];
+  for (i = 0; i < 80; i++) {
+    if (i >= 16) {
+      t = InternalState.Buffer[(i + 13) & 15] ^
+          InternalState.Buffer[(i + 8) & 15] ^
+          InternalState.Buffer[(i + 2) & 15] ^ InternalState.Buffer[i & 15];
+      InternalState.Buffer[i & 15] = rol32(t, 1);
+    }
+    if (i < 20) {
+      t = (d ^ (b & (c ^ d))) + SHA1_K0;
+    } else if (i < 40) {
+      t = (b ^ c ^ d) + SHA1_K20;
+    } else if (i < 60) {
+      t = ((b & c) | (d & (b | c))) + SHA1_K40;
+    } else {
+      t = (b ^ c ^ d) + SHA1_K60;
+    }
+    t += rol32(a, 5) + e + InternalState.Buffer[i & 15];
+    e = d;
+    d = c;
+    c = rol32(b, 30);
+    b = a;
+    a = t;
+  }
+  InternalState.State[0] += a;
+  InternalState.State[1] += b;
+  InternalState.State[2] += c;
+  InternalState.State[3] += d;
+  InternalState.State[4] += e;
+}
+
+void SHA1::addUncounted(uint8_t data) {
+  uint8_t *const b = (uint8_t *)InternalState.Buffer;
+#ifdef SHA_BIG_ENDIAN
+  b[InternalState.BufferOffset] = data;
+#else
+  b[InternalState.BufferOffset ^ 3] = data;
+#endif
+  InternalState.BufferOffset++;
+  if (InternalState.BufferOffset == BLOCK_LENGTH) {
+    hashBlock();
+    InternalState.BufferOffset = 0;
+  }
+}
+
+void SHA1::writebyte(uint8_t data) {
+  ++InternalState.ByteCount;
+  addUncounted(data);
+}
+
+void SHA1::write(const char *data, size_t len) {
+  for (; len--;)
+    writebyte((uint8_t)*data++);
+}
+
+void SHA1::pad() {
+  // Implement SHA-1 padding (fips180-2 §5.1.1)
+
+  // Pad with 0x80 followed by 0x00 until the end of the block
+  addUncounted(0x80);
+  while (InternalState.BufferOffset != 56)
+    addUncounted(0x00);
+
+  // Append length in the last 8 bytes
+  addUncounted(0); // We're only using 32 bit lengths
+  addUncounted(0); // But SHA-1 supports 64 bit lengths
+  addUncounted(0); // So zero pad the top bits
+  addUncounted(InternalState.ByteCount >> 29); // Shifting to multiply by 8
+  addUncounted(InternalState.ByteCount >>
+               21); // as SHA-1 supports bitstreams as well as
+  addUncounted(InternalState.ByteCount >> 13); // byte.
+  addUncounted(InternalState.ByteCount >> 5);
+  addUncounted(InternalState.ByteCount << 3);
+}
+#include <cstdio>
+StringRef SHA1::result() {
+  auto StateToRestore = InternalState;
+
+  // Pad to complete the last block
+  pad();
+
+#ifndef SHA_BIG_ENDIAN
+  // Swap byte order back
+  for (int i = 0; i < 5; i++) {
+    HashResult[i] = (((InternalState.State[i]) << 24) & 0xff000000) |
+                    (((InternalState.State[i]) << 8) & 0x00ff0000) |
+                    (((InternalState.State[i]) >> 8) & 0x0000ff00) |
+                    (((InternalState.State[i]) >> 24) & 0x000000ff);
+  }
+#else
+  // Just copy the current state
+  for (int i = 0; i < 5; i++) {
+    HashResult[i] = InternalState.State[i];
+  }
+#endif
+
+  // Restore the state
+  InternalState = StateToRestore;
+
+  // Return pointer to hash (20 characters)
+  return StringRef((char *)HashResult, HASH_LENGTH);
+}
Index: unittests/Support/CMakeLists.txt
===================================================================
--- unittests/Support/CMakeLists.txt
+++ unittests/Support/CMakeLists.txt
@@ -51,6 +51,7 @@
   formatted_raw_ostream_test.cpp
   raw_ostream_test.cpp
   raw_pwrite_stream_test.cpp
+  raw_sha1_ostream_test.cpp
   )
 
 # ManagedStatic.cpp uses <pthread>.
Index: unittests/Support/raw_sha1_ostream_test.cpp
===================================================================
--- /dev/null
+++ unittests/Support/raw_sha1_ostream_test.cpp
@@ -0,0 +1,66 @@
+//==- llvm/unittest/Support/raw_sha1_ostream_test.cpp - SHA1 stream tests -===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_sha1_ostream.h"
+
+#include <string>
+
+using namespace llvm;
+
+static std::string toHex(StringRef Input) {
+  static const char *const LUT = "0123456789ABCDEF";
+  size_t Length = Input.size();
+
+  std::string Output;
+  Output.reserve(2 * Length);
+  for (size_t i = 0; i < Length; ++i) {
+    const unsigned char c = Input[i];
+    Output.push_back(LUT[c >> 4]);
+    Output.push_back(LUT[c & 15]);
+  }
+  return Output;
+}
+
+TEST(raw_sha1_ostreamTest, Basic) {
+  llvm::raw_sha1_ostream Sha1Stream;
+  Sha1Stream << "Hello World!";
+  auto Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("2EF7BDE608CE5404E97D5F042F95F89F1C232871", Hash);
+}
+
+TEST(raw_sha1_ostreamTest, Intermediate) {
+  llvm::raw_sha1_ostream Sha1Stream;
+  Sha1Stream << "Hello";
+  auto Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("F7FF9E8B7BB2E09B70935A5D785E0CC5D9D0ABF0", Hash);
+
+  Sha1Stream << " World!";
+  Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("2EF7BDE608CE5404E97D5F042F95F89F1C232871", Hash);
+}
+
+TEST(raw_sha1_ostreamTest, Reset) {
+  llvm::raw_sha1_ostream Sha1Stream;
+  Sha1Stream << "Hello";
+  auto Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("F7FF9E8B7BB2E09B70935A5D785E0CC5D9D0ABF0", Hash);
+
+  Sha1Stream.resetHash();
+  Sha1Stream << " World!";
+  Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("7447F2A5A42185C8CF91E632789C431830B59067", Hash);
+}