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diff --git a/rand/rand_pcg/src/pcg64.rs b/rand/rand_pcg/src/pcg64.rs
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+// Copyright 2018 Developers of the Rand project.
+// Copyright 2017 Paul Dicker.
+// Copyright 2014-2017 Melissa O'Neill and PCG Project contributors
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! PCG random number generators
+
+use core::fmt;
+use core::mem::transmute;
+use rand_core::{RngCore, SeedableRng, Error, le, impls};
+
+// This is the default multiplier used by PCG for 64-bit state.
+const MULTIPLIER: u64 = 6364136223846793005;
+
+/// A PCG random number generator (XSH RR 64/32 (LCG) variant).
+///
+/// Permuted Congruential Generator with 64-bit state, internal Linear
+/// Congruential Generator, and 32-bit output via "xorshift high (bits),
+/// random rotation" output function.
+///
+/// This is a 64-bit LCG with explicitly chosen stream with the PCG-XSH-RR
+/// output function. This combination is the standard `pcg32`.
+///
+/// Despite the name, this implementation uses 16 bytes (128 bit) space
+/// comprising 64 bits of state and 64 bits stream selector. These are both set
+/// by `SeedableRng`, using a 128-bit seed.
+#[derive(Clone)]
+#[cfg_attr(feature="serde1", derive(Serialize,Deserialize))]
+pub struct Lcg64Xsh32 {
+    state: u64,
+    increment: u64,
+}
+
+/// `Lcg64Xsh32` is also officially known as `pcg32`.
+pub type Pcg32 = Lcg64Xsh32;
+
+impl Lcg64Xsh32 {
+    /// Construct an instance compatible with PCG seed and stream.
+    ///
+    /// Note that PCG specifies default values for both parameters:
+    ///
+    /// - `state = 0xcafef00dd15ea5e5`
+    /// - `stream = 721347520444481703`
+    pub fn new(state: u64, stream: u64) -> Self {
+        // The increment must be odd, hence we discard one bit:
+        let increment = (stream << 1) | 1;
+        Lcg64Xsh32::from_state_incr(state, increment)
+    }
+
+    #[inline]
+    fn from_state_incr(state: u64, increment: u64) -> Self {
+        let mut pcg = Lcg64Xsh32 { state, increment };
+        // Move away from inital value:
+        pcg.state = pcg.state.wrapping_add(pcg.increment);
+        pcg.step();
+        pcg
+    }
+
+    #[inline]
+    fn step(&mut self) {
+        // prepare the LCG for the next round
+        self.state = self.state
+            .wrapping_mul(MULTIPLIER)
+            .wrapping_add(self.increment);
+    }
+}
+
+// Custom Debug implementation that does not expose the internal state
+impl fmt::Debug for Lcg64Xsh32 {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Lcg64Xsh32 {{}}")
+    }
+}
+
+/// We use a single 127-bit seed to initialise the state and select a stream.
+/// One `seed` bit (lowest bit of `seed[8]`) is ignored.
+impl SeedableRng for Lcg64Xsh32 {
+    type Seed = [u8; 16];
+
+    fn from_seed(seed: Self::Seed) -> Self {
+        let mut seed_u64 = [0u64; 2];
+        le::read_u64_into(&seed, &mut seed_u64);
+
+        // The increment must be odd, hence we discard one bit:
+        Lcg64Xsh32::from_state_incr(seed_u64[0], seed_u64[1] | 1)
+    }
+}
+
+impl RngCore for Lcg64Xsh32 {
+    #[inline]
+    fn next_u32(&mut self) -> u32 {
+        let state = self.state;
+        self.step();
+
+        // Output function XSH RR: xorshift high (bits), followed by a random rotate
+        // Constants are for 64-bit state, 32-bit output
+        const ROTATE: u32 = 59; // 64 - 5
+        const XSHIFT: u32 = 18; // (5 + 32) / 2
+        const SPARE: u32 = 27;  // 64 - 32 - 5
+
+        let rot = (state >> ROTATE) as u32;
+        let xsh = (((state >> XSHIFT) ^ state) >> SPARE) as u32;
+        xsh.rotate_right(rot)
+    }
+
+    #[inline]
+    fn next_u64(&mut self) -> u64 {
+        impls::next_u64_via_u32(self)
+    }
+
+    #[inline]
+    fn fill_bytes(&mut self, dest: &mut [u8]) {
+        // specialisation of impls::fill_bytes_via_next; approx 40% faster
+        let mut left = dest;
+        while left.len() >= 4 {
+            let (l, r) = {left}.split_at_mut(4);
+            left = r;
+            let chunk: [u8; 4] = unsafe {
+                transmute(self.next_u32().to_le())
+            };
+            l.copy_from_slice(&chunk);
+        }
+        let n = left.len();
+        if n > 0 {
+            let chunk: [u8; 4] = unsafe {
+                transmute(self.next_u32().to_le())
+            };
+            left.copy_from_slice(&chunk[..n]);
+        }
+    }
+
+    #[inline]
+    fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
+        Ok(self.fill_bytes(dest))
+    }
+}