diff --git a/compiler-rt/lib/fuzzer/FuzzerMutate.cpp b/compiler-rt/lib/fuzzer/FuzzerMutate.cpp
--- a/compiler-rt/lib/fuzzer/FuzzerMutate.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerMutate.cpp
@@ -379,6 +379,67 @@
   return Size;
 }
 
+#define INTERESTING_8                                                          \
+  -128,    /* Overflow signed 8-bit when decremented  */                       \
+      -1,  /*                                         */                       \
+      0,   /*                                         */                       \
+      1,   /*                                         */                       \
+      16,  /* One-off with common buffer size         */                       \
+      32,  /* One-off with common buffer size         */                       \
+      64,  /* One-off with common buffer size         */                       \
+      100, /* One-off with common buffer size         */                       \
+      127  /* Overflow signed 8-bit when incremented  */
+
+#define INTERESTING_16                                                         \
+  -32768,   /* Overflow signed 16-bit when decremented */                      \
+      -129, /* Overflow signed 8-bit                   */                      \
+      128,  /* Overflow signed 8-bit                   */                      \
+      255,  /* Overflow unsig 8-bit when incremented   */                      \
+      256,  /* Overflow unsig 8-bit                    */                      \
+      512,  /* One-off with common buffer size         */                      \
+      1000, /* One-off with common buffer size         */                      \
+      1024, /* One-off with common buffer size         */                      \
+      4096, /* One-off with common buffer size         */                      \
+      32767 /* Overflow signed 16-bit when incremented */
+
+#define INTERESTING_32                                                         \
+  -2147483648LL,  /* Overflow signed 32-bit when decremented */                \
+      -100663046, /* Large negative number (endian-agnostic) */                \
+      -32769,     /* Overflow signed 16-bit                  */                \
+      32768,      /* Overflow signed 16-bit                  */                \
+      65535,      /* Overflow unsig 16-bit when incremented  */                \
+      65536,      /* Overflow unsig 16 bit                   */                \
+      100663045,  /* Large positive number (endian-agnostic) */                \
+      2147483647  /* Overflow signed 32-bit when incremented */
+
+template <class T> class MagicInt8 {
+public:
+  static constexpr T Values[] = {INTERESTING_8};
+};
+
+template <class T> class MagicInt16 {
+public:
+  static constexpr T Values[] = {INTERESTING_8, INTERESTING_16};
+};
+
+template <class T> class MagicInt32 {
+public:
+  static constexpr T Values[] = {INTERESTING_8, INTERESTING_16, INTERESTING_32};
+};
+
+// Definitions
+template <class T> constexpr T MagicInt8<T>::Values[];
+template <class T> constexpr T MagicInt16<T>::Values[];
+template <class T> constexpr T MagicInt32<T>::Values[];
+
+template <class T>
+using MagicInt = typename std::conditional<
+    sizeof(T) == 1, MagicInt8<int8_t>,
+    typename std::conditional<
+        sizeof(T) == 2, MagicInt16<int16_t>,
+        typename std::conditional<sizeof(T) == 4, MagicInt32<int32_t>,
+                                  MagicInt32<int64_t>>::type>::type>::type;
+
 template<class T>
 size_t ChangeBinaryInteger(uint8_t *Data, size_t Size, Random &Rand) {
   if (Size < sizeof(T)) return 0;
@@ -389,6 +450,13 @@
     Val = Size;
     if (Rand.RandBool())
       Val = Bswap(Val);
+  } else if (Rand.RandBool()) {
+    auto SignedVal =
+        MagicInt<T>::Values[Rand(sizeof(MagicInt<T>::Values) / sizeof(T))];
+    memcpy(&Val, &SignedVal, sizeof(SignedVal));
+    if (Rand.RandBool()) {
+      Val = Bswap(Val);
+    }
   } else {
     memcpy(&Val, Data + Off, sizeof(Val));
     T Add = Rand(21);
diff --git a/compiler-rt/test/fuzzer/OverwriteBytesMain.cpp b/compiler-rt/test/fuzzer/OverwriteBytesMain.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/fuzzer/OverwriteBytesMain.cpp
@@ -0,0 +1,9 @@
+#include <cstdint>
+#include <cstdio>
+
+#include "OverwriteBytesTest.h"
+
+int main(int argc, char **argv) {
+  fwrite(SeedInput, sizeof(SeedInput[0]), sizeof(SeedInput), stdout);
+  return 0;
+}
diff --git a/compiler-rt/test/fuzzer/OverwriteBytesTest.h b/compiler-rt/test/fuzzer/OverwriteBytesTest.h
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/fuzzer/OverwriteBytesTest.h
@@ -0,0 +1,5 @@
+uint8_t SeedInput[] = {
+    0xba, 0xe3, 0x92, 0x7c, 0x80, 0x86, 0x73, 0x0f, 0xf2, 0x83, 0x23, 0x0f,
+    0xf5, 0x17, 0x4c, 0x08, 0xf2, 0x83, 0x23, 0x0f, 0xd8, 0x71, 0x58, 0x1c,
+    0xb9, 0x8d, 0xf1, 0x0e, 0x80, 0x86, 0x73, 0x0f, 0xf0, 0x83, 0x23, 0x0f,
+};
diff --git a/compiler-rt/test/fuzzer/OverwriteBytesTest.cpp b/compiler-rt/test/fuzzer/OverwriteBytesTest.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/fuzzer/OverwriteBytesTest.cpp
@@ -0,0 +1,33 @@
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <cassert>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+#include <algorithm>
+#include <vector>
+
+#include "OverwriteBytesTest.h"
+
+#define MAGIC_BYTE_VALUE 0x1
+#define MAGIC_BYTE_OFFSET 0xf
+
+static volatile int *Nil = nullptr;
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  if (Size != sizeof(SeedInput)) {
+    return 0;
+  }
+
+  *(uint64_t *)(SeedInput + MAGIC_BYTE_OFFSET) = MAGIC_BYTE_VALUE;
+
+  if (memmem(Data, Size, SeedInput, Size) == Data) {
+    *Nil = 42; // crash.
+  }
+
+  return 0;
+}
diff --git a/compiler-rt/test/fuzzer/overwrite-bytes.test b/compiler-rt/test/fuzzer/overwrite-bytes.test
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/fuzzer/overwrite-bytes.test
@@ -0,0 +1,9 @@
+REQUIRES: linux, x86_64
+RUN: %cpp_compiler %S/OverwriteBytesTest.cpp -o %t-OverwriteBytesTest
+RUN: %cpp_compiler -fno-sanitize=fuzzer %S/OverwriteBytesMain.cpp -o %t-OverwriteBytesPrintSeed
+RUN: %t-OverwriteBytesPrintSeed > %t-OverwriteBytesTest.seed
+
+RUN: not %run %t-OverwriteBytesTest -seed=1 -use_memmem=0 -mutate_depth=1 -reduce_inputs=0 -runs=10000000 -seed_inputs=%t-OverwriteBytesTest.seed 2>&1 | FileCheck %s
+
+CHECK: ABORTING
+CHECK-NEXT: MS: 1 ChangeBinInt-;