diff --git a/compiler-rt/lib/fuzzer/FuzzerDriver.cpp b/compiler-rt/lib/fuzzer/FuzzerDriver.cpp
--- a/compiler-rt/lib/fuzzer/FuzzerDriver.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerDriver.cpp
@@ -709,6 +709,8 @@
     Options.DataFlowTrace = Flags.data_flow_trace;
   if (Flags.features_dir)
     Options.FeaturesDir = Flags.features_dir;
+  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/compiler-rt/lib/fuzzer/FuzzerFlags.def b/compiler-rt/lib/fuzzer/FuzzerFlags.def
--- a/compiler-rt/lib/fuzzer/FuzzerFlags.def
+++ b/compiler-rt/lib/fuzzer/FuzzerFlags.def
@@ -74,6 +74,8 @@
   "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, "internal flag. Used to dump"
+  " a corpus mutation graph on disk.")
 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/compiler-rt/lib/fuzzer/FuzzerIO.h b/compiler-rt/lib/fuzzer/FuzzerIO.h
--- a/compiler-rt/lib/fuzzer/FuzzerIO.h
+++ b/compiler-rt/lib/fuzzer/FuzzerIO.h
@@ -29,6 +29,10 @@
 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 AppendToFile(const Unit &U, const std::string &Path);
+
 void ReadDirToVectorOfUnits(const char *Path, Vector<Unit> *V,
                             long *Epoch, size_t MaxSize, bool ExitOnError);
 
diff --git a/compiler-rt/lib/fuzzer/FuzzerIO.cpp b/compiler-rt/lib/fuzzer/FuzzerIO.cpp
--- a/compiler-rt/lib/fuzzer/FuzzerIO.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerIO.cpp
@@ -77,6 +77,23 @@
   fclose(Out);
 }
 
+void AppendToFile(const Unit &U, const std::string &Path) {
+  AppendToFile(U.data(), U.size(), Path);
+}
+
+void AppendToFile(const std::string &Data, const std::string &Path) {
+  AppendToFile(reinterpret_cast<const uint8_t *>(Data.c_str()), 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/compiler-rt/lib/fuzzer/FuzzerLoop.cpp b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
--- a/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerLoop.cpp
@@ -463,6 +463,40 @@
              DirPlusFile(FeaturesDir, NewFile));
 }
 
+static void WriteEdgeToMutationGraphFile(const std::string &MutationGraphFile,
+                                         const InputInfo *II,
+                                         const InputInfo *BaseII,
+                                         const std::string &MS) {
+  if (MutationGraphFile.empty())
+    return;
+
+  Unit U;
+
+  // Add a new vertex.
+  std::string newVertex;
+  newVertex.append("V" + Sha1ToString(II->Sha1));
+  newVertex.append(" [label=\"" + Sha1ToString(II->Sha1) + "\"];\n");
+
+  size_t insertAt = U.size();
+  U.resize(insertAt + newVertex.size());
+  memcpy(U.data() + insertAt, newVertex.c_str(), newVertex.size());
+
+  // Add a new edge if there is base input.
+  if (BaseII) {
+    std::string newEdge;
+    newEdge.append("V" + Sha1ToString(BaseII->Sha1));
+    newEdge.append(" -> ");
+    newEdge.append("V" + Sha1ToString(II->Sha1));
+    newEdge.append(" [label=\"" + MS + "\"];\n");
+
+    insertAt = U.size();
+    U.resize(insertAt + newEdge.size());
+    memcpy(U.data() + insertAt, newEdge.c_str(), newEdge.size());
+  }
+
+  AppendToFile(U, MutationGraphFile);
+}
+
 bool Fuzzer::RunOne(const uint8_t *Data, size_t Size, bool MayDeleteFile,
                     InputInfo *II, bool *FoundUniqFeatures) {
   if (!Size)
@@ -494,6 +528,8 @@
                                     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/compiler-rt/lib/fuzzer/FuzzerMutate.h b/compiler-rt/lib/fuzzer/FuzzerMutate.h
--- a/compiler-rt/lib/fuzzer/FuzzerMutate.h
+++ b/compiler-rt/lib/fuzzer/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/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
@@ -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/compiler-rt/lib/fuzzer/FuzzerOptions.h b/compiler-rt/lib/fuzzer/FuzzerOptions.h
--- a/compiler-rt/lib/fuzzer/FuzzerOptions.h
+++ b/compiler-rt/lib/fuzzer/FuzzerOptions.h
@@ -56,6 +56,7 @@
   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;
diff --git a/compiler-rt/test/fuzzer/mutation-graph.test b/compiler-rt/test/fuzzer/mutation-graph.test
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/fuzzer/mutation-graph.test
@@ -0,0 +1,11 @@
+REQUIRES: linux, x86_64
+RUN: %cpp_compiler %S/SimpleTest.cpp -o %t-SimpleTest
+
+RUN: rm -rf %t-SimpleTestGraph
+
+RUN: not %run %t-SimpleTest -mutation_graph_file=%t-SimpleTestGraph 2>&1 | FileCheck %s
+CHECK: BINGO
+
+RUN: cat %t-SimpleTestGraph | FileCheck %s --check-prefix=GRAPH
+GRAPH: V{{.*}} [label="{{.*}}"];
+GRAPH: V{{.*}} -> V{{.*}} [label="{{.*}}"];