diff --git a/FuzzerDriver.cpp b/FuzzerDriver.cpp
index caafd1d..57df123 100644
--- a/FuzzerDriver.cpp
+++ b/FuzzerDriver.cpp
@@ -755,6 +755,8 @@
     Options.FeaturesDir = Flags.features_dir;
     ValidateDirectoryExists(Options.FeaturesDir, Flags.create_missing_dirs);
   }
+  if (Flags.mutation_graph_file)
+    Options.MutationGraphFile = Flags.mutation_graph_file;
   if (Flags.collect_data_flow)
     Options.CollectDataFlow = Flags.collect_data_flow;
   if (Flags.stop_file)
diff --git a/FuzzerFlags.def b/FuzzerFlags.def
index fdb8362..c9a787e 100644
--- a/FuzzerFlags.def
+++ b/FuzzerFlags.def
@@ -88,6 +88,11 @@
   "Every time a new input is added to the corpus, a corresponding file in the features_dir"
   " is created containing the unique features of that input."
   " Features are stored in binary format.")
+FUZZER_FLAG_STRING(mutation_graph_file, "Saves a graph (in DOT format) to"
+  " mutation_graph_file. The graph contains a vertex for each input that has"
+  " unique coverage; directed edges are provided between parents and children"
+  " where the child has unique coverage, and are recorded with the type of"
+  " mutation that caused the child.")
 FUZZER_FLAG_INT(use_counters, 1, "Use coverage counters")
 FUZZER_FLAG_INT(use_memmem, 1,
                 "Use hints from intercepting memmem, strstr, etc")
diff --git a/FuzzerIO.cpp b/FuzzerIO.cpp
index c3330c3..54a7219 100644
--- a/FuzzerIO.cpp
+++ b/FuzzerIO.cpp
@@ -77,6 +77,19 @@
   fclose(Out);
 }
 
+void AppendToFile(const std::string &Data, const std::string &Path) {
+  AppendToFile(reinterpret_cast<const uint8_t *>(Data.data()), Data.size(),
+               Path);
+}
+
+void AppendToFile(const uint8_t *Data, size_t Size, const std::string &Path) {
+  FILE *Out = fopen(Path.c_str(), "a");
+  if (!Out)
+    return;
+  fwrite(Data, sizeof(Data[0]), Size, Out);
+  fclose(Out);
+}
+
 void ReadDirToVectorOfUnits(const char *Path, Vector<Unit> *V,
                             long *Epoch, size_t MaxSize, bool ExitOnError) {
   long E = Epoch ? *Epoch : 0;
diff --git a/FuzzerIO.h b/FuzzerIO.h
index 6e3a0b4..abd2511 100644
--- a/FuzzerIO.h
+++ b/FuzzerIO.h
@@ -29,6 +29,9 @@
 void WriteToFile(const std::string &Data, const std::string &Path);
 void WriteToFile(const Unit &U, const std::string &Path);
 
+void AppendToFile(const uint8_t *Data, size_t Size, const std::string &Path);
+void AppendToFile(const std::string &Data, const std::string &Path);
+
 void ReadDirToVectorOfUnits(const char *Path, Vector<Unit> *V,
                             long *Epoch, size_t MaxSize, bool ExitOnError);
 
diff --git a/FuzzerLoop.cpp b/FuzzerLoop.cpp
index f9986dd..ce8c2fb 100644
--- a/FuzzerLoop.cpp
+++ b/FuzzerLoop.cpp
@@ -463,6 +463,37 @@
              DirPlusFile(FeaturesDir, NewFile));
 }
 
+static void WriteEdgeToMutationGraphFile(const std::string &MutationGraphFile,
+                                         const InputInfo *II,
+                                         const InputInfo *BaseII,
+                                         const std::string &MS) {
+  if (MutationGraphFile.empty())
+    return;
+
+  std::string Sha1 = Sha1ToString(II->Sha1);
+
+  std::string OutputString;
+
+  // Add a new vertex.
+  OutputString.append("\"");
+  OutputString.append(Sha1);
+  OutputString.append("\"\n");
+
+  // Add a new edge if there is base input.
+  if (BaseII) {
+    std::string BaseSha1 = Sha1ToString(BaseII->Sha1);
+    OutputString.append("\"");
+    OutputString.append(BaseSha1);
+    OutputString.append("\" -> \"");
+    OutputString.append(Sha1);
+    OutputString.append("\" [label=\"");
+    OutputString.append(MS);
+    OutputString.append("\"];\n");
+  }
+
+  AppendToFile(OutputString, MutationGraphFile);
+}
+
 bool Fuzzer::RunOne(const uint8_t *Data, size_t Size, bool MayDeleteFile,
                     InputInfo *II, bool ForceAddToCorpus,
                     bool *FoundUniqFeatures) {
@@ -497,6 +528,8 @@
                            TimeOfUnit, UniqFeatureSetTmp, DFT, II);
     WriteFeatureSetToFile(Options.FeaturesDir, Sha1ToString(NewII->Sha1),
                           NewII->UniqFeatureSet);
+    WriteEdgeToMutationGraphFile(Options.MutationGraphFile, NewII, II,
+                                 MD.MutationSequence());
     return true;
   }
   if (II && FoundUniqFeaturesOfII &&
diff --git a/FuzzerMutate.cpp b/FuzzerMutate.cpp
index df9ada4..121b450 100644
--- a/FuzzerMutate.cpp
+++ b/FuzzerMutate.cpp
@@ -494,6 +494,15 @@
   }
 }
 
+std::string MutationDispatcher::MutationSequence() {
+  std::string MS;
+  for (auto M : CurrentMutatorSequence) {
+    MS += M.Name;
+    MS += "-";
+  }
+  return MS;
+}
+
 size_t MutationDispatcher::Mutate(uint8_t *Data, size_t Size, size_t MaxSize) {
   return MutateImpl(Data, Size, MaxSize, Mutators);
 }
diff --git a/FuzzerMutate.h b/FuzzerMutate.h
index 6cbce80..3ce3159 100644
--- a/FuzzerMutate.h
+++ b/FuzzerMutate.h
@@ -26,6 +26,8 @@
   void StartMutationSequence();
   /// Print the current sequence of mutations.
   void PrintMutationSequence();
+  /// Return the current sequence of mutations.
+  std::string MutationSequence();
   /// Indicate that the current sequence of mutations was successful.
   void RecordSuccessfulMutationSequence();
   /// Mutates data by invoking user-provided mutator.
diff --git a/FuzzerOptions.h b/FuzzerOptions.h
index b17a747..706e1c6 100644
--- a/FuzzerOptions.h
+++ b/FuzzerOptions.h
@@ -59,6 +59,7 @@
   std::string DataFlowTrace;
   std::string CollectDataFlow;
   std::string FeaturesDir;
+  std::string MutationGraphFile;
   std::string StopFile;
   bool SaveArtifacts = true;
   bool PrintNEW = true; // Print a status line when new units are found;