diff --git a/openjdkjvmti/ti_extension.cc b/openjdkjvmti/ti_extension.cc
index f12cb0a..08667c3 100644
--- a/openjdkjvmti/ti_extension.cc
+++ b/openjdkjvmti/ti_extension.cc
@@ -42,6 +42,7 @@
 #include "ti_heap.h"
 #include "ti_logging.h"
 #include "ti_monitor.h"
+#include "ti_search.h"
 
 #include "thread-inl.h"
 
@@ -327,6 +328,54 @@
     return error;
   }
 
+  // AddToDexClassLoader
+  error = add_extension(
+      reinterpret_cast<jvmtiExtensionFunction>(SearchUtil::AddToDexClassLoader),
+      "com.android.art.classloader.add_to_dex_class_loader",
+      "Adds a dexfile to a given dalvik.system.BaseDexClassLoader in a manner similar to"
+      " AddToSystemClassLoader.",
+      {
+        { "classloader", JVMTI_KIND_IN, JVMTI_TYPE_JOBJECT, false },
+        { "segment", JVMTI_KIND_IN_PTR, JVMTI_TYPE_CCHAR, false },
+      },
+      {
+         ERR(NULL_POINTER),
+         ERR(CLASS_LOADER_UNSUPPORTED),
+         ERR(ILLEGAL_ARGUMENT),
+         ERR(WRONG_PHASE),
+      });
+  if (error != ERR(NONE)) {
+    return error;
+  }
+
+  // AddToDexClassLoaderInMemory requires memfd_create which non-linux doesn't have. The code will
+  // still all link but since it will only ever return ERR(INTERNAL) we might as well not even
+  // advertise the extension.
+  // TODO Support non-linux in some way.
+#ifdef __linux__
+  // AddToDexClassLoaderInMemory
+  error = add_extension(
+      reinterpret_cast<jvmtiExtensionFunction>(SearchUtil::AddToDexClassLoaderInMemory),
+      "com.android.art.classloader.add_to_dex_class_loader_in_memory",
+      "Adds a dexfile buffer to a given dalvik.system.BaseDexClassLoader in a manner similar to"
+      " AddToSystemClassLoader. This may only be done during the LIVE phase. The buffer is copied"
+      " and the caller is responsible for deallocating it after this call.",
+      {
+        { "classloader", JVMTI_KIND_IN, JVMTI_TYPE_JOBJECT, false },
+        { "dex_bytes", JVMTI_KIND_IN_BUF, JVMTI_TYPE_CCHAR, false },
+        { "dex_bytes_len", JVMTI_KIND_IN, JVMTI_TYPE_JINT, false },
+      },
+      {
+         ERR(NULL_POINTER),
+         ERR(CLASS_LOADER_UNSUPPORTED),
+         ERR(ILLEGAL_ARGUMENT),
+         ERR(WRONG_PHASE),
+      });
+  if (error != ERR(NONE)) {
+    return error;
+  }
+#endif
+
   // Copy into output buffer.
 
   *extension_count_ptr = ext_vector.size();
diff --git a/openjdkjvmti/ti_search.cc b/openjdkjvmti/ti_search.cc
index 2187825..1eadf11 100644
--- a/openjdkjvmti/ti_search.cc
+++ b/openjdkjvmti/ti_search.cc
@@ -29,6 +29,9 @@
  * questions.
  */
 
+#include <sstream>
+#include <unistd.h>
+
 #include "ti_search.h"
 
 #include "jni.h"
@@ -37,6 +40,9 @@
 #include "art_jvmti.h"
 #include "base/enums.h"
 #include "base/macros.h"
+#include "base/memfd.h"
+#include "base/os.h"
+#include "base/unix_file/fd_file.h"
 #include "class_linker.h"
 #include "dex/art_dex_file_loader.h"
 #include "dex/dex_file.h"
@@ -249,8 +255,121 @@
   return ERR(NONE);
 }
 
-jvmtiError SearchUtil::AddToSystemClassLoaderSearch(jvmtiEnv* jvmti_env ATTRIBUTE_UNUSED,
-                                                    const char* segment) {
+jvmtiError SearchUtil::AddToDexClassLoaderInMemory(jvmtiEnv* jvmti_env,
+                                                   jobject classloader,
+                                                   const char* dex_bytes,
+                                                   jint dex_bytes_length) {
+  if (jvmti_env == nullptr) {
+    return ERR(INVALID_ENVIRONMENT);
+  } else if (art::Thread::Current() == nullptr) {
+    return ERR(UNATTACHED_THREAD);
+  } else if (classloader == nullptr) {
+    return ERR(NULL_POINTER);
+  } else if (dex_bytes == nullptr) {
+    return ERR(NULL_POINTER);
+  } else if (dex_bytes_length <= 0) {
+    return ERR(ILLEGAL_ARGUMENT);
+  }
+
+  jvmtiPhase phase = PhaseUtil::GetPhaseUnchecked();
+
+  // TODO We really should try to support doing this during the ON_LOAD phase.
+  if (phase != jvmtiPhase::JVMTI_PHASE_LIVE) {
+    JVMTI_LOG(INFO, jvmti_env) << "Cannot add buffers to classpath during ON_LOAD phase to "
+                               << "prevent file-descriptor leaking.";
+    return ERR(WRONG_PHASE);
+  }
+
+  // We have java APIs for adding files to the classpath, we might as well use them. It simplifies a
+  // lot of code as well.
+
+  // Create a memfd
+  art::File file(art::memfd_create("JVMTI InMemory Added dex file", 0), /*check-usage*/true);
+  if (file.Fd() < 0) {
+    char* reason = strerror(errno);
+    JVMTI_LOG(ERROR, jvmti_env) << "Unable to create memfd due to " << reason;
+    return ERR(INTERNAL);
+  }
+  // Fill it with the buffer.
+  if (!file.WriteFully(dex_bytes, dex_bytes_length) || file.Flush() != 0) {
+    JVMTI_LOG(ERROR, jvmti_env) << "Failed to write to memfd!";
+    return ERR(INTERNAL);
+  }
+  // Get the filename in procfs.
+  std::ostringstream oss;
+  oss << "/proc/self/fd/" << file.Fd();
+  std::string seg(oss.str());
+  // Use common code.
+
+  jvmtiError result = AddToDexClassLoader(jvmti_env, classloader, seg.c_str());
+  // We have either loaded the dex file and have a new MemMap pointing to the same pages or loading
+  // has failed and the memory isn't needed anymore. Either way we can close the memfd we created
+  // and return.
+  if (file.Close() != 0) {
+    JVMTI_LOG(WARNING, jvmti_env) << "Failed to close memfd!";
+  }
+  return result;
+}
+
+jvmtiError SearchUtil::AddToDexClassLoader(jvmtiEnv* jvmti_env,
+                                           jobject classloader,
+                                           const char* segment) {
+  if (jvmti_env == nullptr) {
+    return ERR(INVALID_ENVIRONMENT);
+  } else if (art::Thread::Current() == nullptr) {
+    return ERR(UNATTACHED_THREAD);
+  } else if (classloader == nullptr) {
+    return ERR(NULL_POINTER);
+  } else if (segment == nullptr) {
+    return ERR(NULL_POINTER);
+  }
+
+  jvmtiPhase phase = PhaseUtil::GetPhaseUnchecked();
+
+  // TODO We really should try to support doing this during the ON_LOAD phase.
+  if (phase != jvmtiPhase::JVMTI_PHASE_LIVE) {
+    JVMTI_LOG(INFO, jvmti_env) << "Cannot add to classpath of arbitrary classloaders during "
+                               << "ON_LOAD phase.";
+    return ERR(WRONG_PHASE);
+  }
+
+  // We'll use BaseDexClassLoader.addDexPath, as it takes care of array resizing etc. As a downside,
+  // exceptions are swallowed.
+
+  art::Thread* self = art::Thread::Current();
+  JNIEnv* env = self->GetJniEnv();
+  if (!env->IsInstanceOf(classloader, art::WellKnownClasses::dalvik_system_BaseDexClassLoader)) {
+    JVMTI_LOG(ERROR, jvmti_env) << "Unable to add " << segment << " to non BaseDexClassLoader!";
+    return ERR(CLASS_LOADER_UNSUPPORTED);
+  }
+
+  jmethodID add_dex_path_id = env->GetMethodID(
+      art::WellKnownClasses::dalvik_system_BaseDexClassLoader,
+      "addDexPath",
+      "(Ljava/lang/String;)V");
+  if (add_dex_path_id == nullptr) {
+    return ERR(INTERNAL);
+  }
+
+  ScopedLocalRef<jstring> dex_path(env, env->NewStringUTF(segment));
+  if (dex_path.get() == nullptr) {
+    return ERR(INTERNAL);
+  }
+  env->CallVoidMethod(classloader, add_dex_path_id, dex_path.get());
+
+  if (env->ExceptionCheck()) {
+    {
+      art::ScopedObjectAccess soa(self);
+      JVMTI_LOG(ERROR, jvmti_env) << "Failed to add " << segment << " to classloader. Error was "
+                                  << self->GetException()->Dump();
+    }
+    env->ExceptionClear();
+    return ERR(ILLEGAL_ARGUMENT);
+  }
+  return OK;
+}
+
+jvmtiError SearchUtil::AddToSystemClassLoaderSearch(jvmtiEnv* jvmti_env, const char* segment) {
   if (segment == nullptr) {
     return ERR(NULL_POINTER);
   }
@@ -266,41 +385,18 @@
     return ERR(WRONG_PHASE);
   }
 
-  jobject sys_class_loader = art::Runtime::Current()->GetSystemClassLoader();
-  if (sys_class_loader == nullptr) {
-    // This is unexpected.
+  jobject loader = art::Runtime::Current()->GetSystemClassLoader();
+  if (loader == nullptr) {
     return ERR(INTERNAL);
   }
 
-  // We'll use BaseDexClassLoader.addDexPath, as it takes care of array resizing etc. As a downside,
-  // exceptions are swallowed.
-
   art::Thread* self = art::Thread::Current();
   JNIEnv* env = self->GetJniEnv();
-  if (!env->IsInstanceOf(sys_class_loader,
-                         art::WellKnownClasses::dalvik_system_BaseDexClassLoader)) {
+  if (!env->IsInstanceOf(loader, art::WellKnownClasses::dalvik_system_BaseDexClassLoader)) {
     return ERR(INTERNAL);
   }
 
-  jmethodID add_dex_path_id = env->GetMethodID(
-      art::WellKnownClasses::dalvik_system_BaseDexClassLoader,
-      "addDexPath",
-      "(Ljava/lang/String;)V");
-  if (add_dex_path_id == nullptr) {
-    return ERR(INTERNAL);
-  }
-
-  ScopedLocalRef<jstring> dex_path(env, env->NewStringUTF(segment));
-  if (dex_path.get() == nullptr) {
-    return ERR(INTERNAL);
-  }
-  env->CallVoidMethod(sys_class_loader, add_dex_path_id, dex_path.get());
-
-  if (env->ExceptionCheck()) {
-    env->ExceptionClear();
-    return ERR(ILLEGAL_ARGUMENT);
-  }
-  return ERR(NONE);
+  return AddToDexClassLoader(jvmti_env, loader, segment);
 }
 
 }  // namespace openjdkjvmti
diff --git a/openjdkjvmti/ti_search.h b/openjdkjvmti/ti_search.h
index 81a28cc..b8d08bf 100644
--- a/openjdkjvmti/ti_search.h
+++ b/openjdkjvmti/ti_search.h
@@ -46,6 +46,12 @@
   static jvmtiError AddToBootstrapClassLoaderSearch(jvmtiEnv* env, const char* segment);
 
   static jvmtiError AddToSystemClassLoaderSearch(jvmtiEnv* env, const char* segment);
+
+  static jvmtiError AddToDexClassLoader(jvmtiEnv* env, jobject classloader, const char* segment);
+  static jvmtiError AddToDexClassLoaderInMemory(jvmtiEnv* env,
+                                                jobject classloader,
+                                                const char* dex_bytes,
+                                                jint dex_bytes_length);
 };
 
 }  // namespace openjdkjvmti
diff --git a/test/1963-add-to-dex-classloader-in-memory/add_to_loader.cc b/test/1963-add-to-dex-classloader-in-memory/add_to_loader.cc
new file mode 100644
index 0000000..1c3f36d
--- /dev/null
+++ b/test/1963-add-to-dex-classloader-in-memory/add_to_loader.cc
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <atomic>
+
+#include "jvmti.h"
+
+// Test infrastructure
+#include "jvmti_helper.h"
+#include "scoped_local_ref.h"
+#include "test_env.h"
+
+namespace art {
+namespace Test1963AddToDexClassLoaderInMemory {
+
+using AddToDexClassLoaderInMemory = jvmtiError (*)(jvmtiEnv* env,
+                                                   jobject loader,
+                                                   const unsigned char* dex_file,
+                                                   jint dex_file_length);
+
+template <typename T> static void Dealloc(T* t) {
+  jvmti_env->Deallocate(reinterpret_cast<unsigned char*>(t));
+}
+
+template <typename T, typename... Rest> static void Dealloc(T* t, Rest... rs) {
+  Dealloc(t);
+  Dealloc(rs...);
+}
+static void DeallocParams(jvmtiParamInfo* params, jint n_params) {
+  for (jint i = 0; i < n_params; i++) {
+    Dealloc(params[i].name);
+  }
+}
+
+AddToDexClassLoaderInMemory GetAddFunction(JNIEnv* env) {
+  // Get the extensions.
+  jint n_ext = 0;
+  jvmtiExtensionFunctionInfo* infos = nullptr;
+  if (JvmtiErrorToException(env, jvmti_env, jvmti_env->GetExtensionFunctions(&n_ext, &infos))) {
+    return nullptr;
+  }
+  AddToDexClassLoaderInMemory result = nullptr;
+  for (jint i = 0; i < n_ext; i++) {
+    jvmtiExtensionFunctionInfo* cur_info = &infos[i];
+    if (strcmp("com.android.art.classloader.add_to_dex_class_loader_in_memory", cur_info->id) ==
+        0) {
+      result = reinterpret_cast<AddToDexClassLoaderInMemory>(cur_info->func);
+    }
+    // Cleanup the cur_info
+    DeallocParams(cur_info->params, cur_info->param_count);
+    Dealloc(cur_info->id, cur_info->short_description, cur_info->params, cur_info->errors);
+  }
+  // Cleanup the array.
+  Dealloc(infos);
+  return result;
+}
+
+extern "C" JNIEXPORT void JNICALL Java_art_Test1963_addToClassLoaderNative(JNIEnv* env,
+                                                                           jclass,
+                                                                           jobject loader,
+                                                                           jobject bytebuffer) {
+  AddToDexClassLoaderInMemory add_func = GetAddFunction(env);
+  if (add_func == nullptr) {
+    env->ThrowNew(env->FindClass("java/lang/RuntimeError"), "Failed to find extension function");
+    return;
+  }
+  JvmtiErrorToException(
+      env,
+      jvmti_env,
+      add_func(jvmti_env,
+               loader,
+               reinterpret_cast<unsigned char*>(env->GetDirectBufferAddress(bytebuffer)),
+               env->GetDirectBufferCapacity(bytebuffer)));
+}
+
+}  // namespace Test1963AddToDexClassLoaderInMemory
+}  // namespace art
diff --git a/test/1963-add-to-dex-classloader-in-memory/expected.txt b/test/1963-add-to-dex-classloader-in-memory/expected.txt
new file mode 100644
index 0000000..c3cc448
--- /dev/null
+++ b/test/1963-add-to-dex-classloader-in-memory/expected.txt
@@ -0,0 +1,19 @@
+ - Run while adding new referenced class.
+ -- Running sayHi before redefinition
+Hello from TestClass sayHi function
+Goodbye from TestClass!
+ -- Adding NewClass to classloader!
+ -- Redefine the TestClass
+ -- call TestClass again, now with NewClass refs
+Hello again from TestClass sayHi function
+Hello from NewClass sayHi function
+Goodbye again from TestClass!
+ - Run without adding new referenced class.
+ -- Running sayHi before redefinition
+Hello from TestClass sayHi function
+Goodbye from TestClass!
+ -- Redefine the TestClass
+ -- call TestClass again, now with NewClass refs
+Hello again from TestClass sayHi function
+ -- Exception caught when running test without new class added! java.lang.NoClassDefFoundError
+ --- java.lang.NoClassDefFoundError At foobar.TestClass.sayHi(TestClass.java:5)
diff --git a/test/1963-add-to-dex-classloader-in-memory/info.txt b/test/1963-add-to-dex-classloader-in-memory/info.txt
new file mode 100644
index 0000000..48df982
--- /dev/null
+++ b/test/1963-add-to-dex-classloader-in-memory/info.txt
@@ -0,0 +1 @@
+Tests we can add dex-file buffers to an existing classloader and the old classes can see them.
\ No newline at end of file
diff --git a/test/1963-add-to-dex-classloader-in-memory/run b/test/1963-add-to-dex-classloader-in-memory/run
new file mode 100755
index 0000000..c6e62ae
--- /dev/null
+++ b/test/1963-add-to-dex-classloader-in-memory/run
@@ -0,0 +1,17 @@
+#!/bin/bash
+#
+# Copyright 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+./default-run "$@" --jvmti
diff --git a/test/1963-add-to-dex-classloader-in-memory/src/Main.java b/test/1963-add-to-dex-classloader-in-memory/src/Main.java
new file mode 100644
index 0000000..3728b45
--- /dev/null
+++ b/test/1963-add-to-dex-classloader-in-memory/src/Main.java
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class Main {
+  public static void main(String[] args) throws Exception {
+    art.Test1963.run();
+  }
+}
diff --git a/test/1963-add-to-dex-classloader-in-memory/src/art/Redefinition.java b/test/1963-add-to-dex-classloader-in-memory/src/art/Redefinition.java
new file mode 120000
index 0000000..81eaf31
--- /dev/null
+++ b/test/1963-add-to-dex-classloader-in-memory/src/art/Redefinition.java
@@ -0,0 +1 @@
+../../../jvmti-common/Redefinition.java
\ No newline at end of file
diff --git a/test/1963-add-to-dex-classloader-in-memory/src/art/Test1963.java b/test/1963-add-to-dex-classloader-in-memory/src/art/Test1963.java
new file mode 100644
index 0000000..a42b3ff
--- /dev/null
+++ b/test/1963-add-to-dex-classloader-in-memory/src/art/Test1963.java
@@ -0,0 +1,243 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package art;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Base64;
+
+public final class Test1963 {
+  private static boolean IS_ART = System.getProperty("java.vm.name").equals("Dalvik");
+
+  private static String TEST_CLASS_NAME = "foobar.TestClass";
+  private static String NEW_CLASS_NAME = "foobar.NewClass";
+
+  /**
+   * base64 encoded class/dex file for
+   * package foobar;
+   * public class NewClass {
+   *   static void sayHi() {
+   *    System.out.println("Hello from NewClass sayHi function");
+   *    TestClass.sayBye();
+   *   }
+   * }
+   */
+  private static byte[] NEW_CLASS_BYTES = Base64.getDecoder().decode(
+      "yv66vgAAADUAIQoABwAPCQAQABEIABIKABMAFAoAFQAWBwAXBwAYAQAGPGluaXQ+AQADKClWAQAE"
+      + "Q29kZQEAD0xpbmVOdW1iZXJUYWJsZQEABXNheUhpAQAKU291cmNlRmlsZQEADU5ld0NsYXNzLmph"
+      + "dmEMAAgACQcAGQwAGgAbAQAiSGVsbG8gZnJvbSBOZXdDbGFzcyBzYXlIaSBmdW5jdGlvbgcAHAwA"
+      + "HQAeBwAfDAAgAAkBAA9mb29iYXIvTmV3Q2xhc3MBABBqYXZhL2xhbmcvT2JqZWN0AQAQamF2YS9s"
+      + "YW5nL1N5c3RlbQEAA291dAEAFUxqYXZhL2lvL1ByaW50U3RyZWFtOwEAE2phdmEvaW8vUHJpbnRT"
+      + "dHJlYW0BAAdwcmludGxuAQAVKExqYXZhL2xhbmcvU3RyaW5nOylWAQAQZm9vYmFyL1Rlc3RDbGFz"
+      + "cwEABnNheUJ5ZQAhAAYABwAAAAAAAgABAAgACQABAAoAAAAdAAEAAQAAAAUqtwABsQAAAAEACwAA"
+      + "AAYAAQAAAAIACAAMAAkAAQAKAAAALAACAAAAAAAMsgACEgO2AAS4AAWxAAAAAQALAAAADgADAAAA"
+      + "BAAIAAUACwAGAAEADQAAAAIADg==");
+  private static byte[] NEW_DEX_BYTES = Base64.getDecoder().decode(
+      "ZGV4CjAzNQA8kzH5IALCWT88v716WlU7OfqukCT2o6WQAwAAcAAAAHhWNBIAAAAAAAAAAOQCAAAQ"
+      + "AAAAcAAAAAcAAACwAAAAAgAAAMwAAAABAAAA5AAAAAUAAADsAAAAAQAAABQBAABcAgAANAEAAIIB"
+      + "AACKAQAArgEAAMEBAADVAQAA7AEAAAACAAAUAgAAKAIAADcCAAA6AgAAPgIAAEMCAABMAgAAVAIA"
+      + "AFsCAAACAAAAAwAAAAQAAAAFAAAABgAAAAcAAAAJAAAACQAAAAYAAAAAAAAACgAAAAYAAAB8AQAA"
+      + "BQACAAsAAAAAAAAAAAAAAAAAAAAOAAAAAQAAAA0AAAACAAEADAAAAAMAAAAAAAAAAAAAAAEAAAAD"
+      + "AAAAAAAAAAgAAAAAAAAA0gIAAAAAAAABAAEAAQAAAHIBAAAEAAAAcBAEAAAADgACAAAAAgAAAHYB"
+      + "AAALAAAAYgAAABoBAQBuIAMAEABxAAIAAAAOAAIADgAEAA54PAABAAAABAAGPGluaXQ+ACJIZWxs"
+      + "byBmcm9tIE5ld0NsYXNzIHNheUhpIGZ1bmN0aW9uABFMZm9vYmFyL05ld0NsYXNzOwASTGZvb2Jh"
+      + "ci9UZXN0Q2xhc3M7ABVMamF2YS9pby9QcmludFN0cmVhbTsAEkxqYXZhL2xhbmcvT2JqZWN0OwAS"
+      + "TGphdmEvbGFuZy9TdHJpbmc7ABJMamF2YS9sYW5nL1N5c3RlbTsADU5ld0NsYXNzLmphdmEAAVYA"
+      + "AlZMAANvdXQAB3ByaW50bG4ABnNheUJ5ZQAFc2F5SGkAdX5+RDh7ImNvbXBpbGF0aW9uLW1vZGUi"
+      + "OiJkZWJ1ZyIsIm1pbi1hcGkiOjEsInNoYS0xIjoiZDMyODJiOGY1NDdjMjM0YzRlNGM5MzA5YzM2"
+      + "Yzc5NWEyOTg1NmVhYiIsInZlcnNpb24iOiIxLjYuMS1kZXYifQAAAAIAAIGABLQCAQjMAgAAAAAO"
+      + "AAAAAAAAAAEAAAAAAAAAAQAAABAAAABwAAAAAgAAAAcAAACwAAAAAwAAAAIAAADMAAAABAAAAAEA"
+      + "AADkAAAABQAAAAUAAADsAAAABgAAAAEAAAAUAQAAASAAAAIAAAA0AQAAAyAAAAIAAAByAQAAARAA"
+      + "AAEAAAB8AQAAAiAAABAAAACCAQAAACAAAAEAAADSAgAAAxAAAAEAAADgAgAAABAAAAEAAADkAgAA");
+  /**
+   * base64 encoded class/dex file for
+   * package foobar;
+   * public class TestClass {
+   *   public static void sayHi() {
+   *    System.out.println("Hello again from TestClass sayHi function");
+   *    TestClass.sayBye();
+   *   }
+   *   static void sayBye() {
+   *    System.out.println("Goodbye from TestClass!");
+   *   }
+   * }
+   */
+  private static byte[] CLASS_BYTES = Base64.getDecoder().decode(
+      "yv66vgAAADUAIQoACAARCQASABMIABQKABUAFgoABwAXCAAYBwAZBwAaAQAGPGluaXQ+AQADKClW"
+      + "AQAEQ29kZQEAD0xpbmVOdW1iZXJUYWJsZQEABXNheUhpAQAGc2F5QnllAQAKU291cmNlRmlsZQEA"
+      + "DlRlc3RDbGFzcy5qYXZhDAAJAAoHABsMABwAHQEAI0hlbGxvIGZyb20gVGVzdENsYXNzIHNheUhp"
+      + "IGZ1bmN0aW9uBwAeDAAfACAMAA4ACgEAF0dvb2RieWUgZnJvbSBUZXN0Q2xhc3MhAQAQZm9vYmFy"
+      + "L1Rlc3RDbGFzcwEAEGphdmEvbGFuZy9PYmplY3QBABBqYXZhL2xhbmcvU3lzdGVtAQADb3V0AQAV"
+      + "TGphdmEvaW8vUHJpbnRTdHJlYW07AQATamF2YS9pby9QcmludFN0cmVhbQEAB3ByaW50bG4BABUo"
+      + "TGphdmEvbGFuZy9TdHJpbmc7KVYAIQAHAAgAAAAAAAMAAQAJAAoAAQALAAAAHQABAAEAAAAFKrcA"
+      + "AbEAAAABAAwAAAAGAAEAAAACAAkADQAKAAEACwAAACwAAgAAAAAADLIAAhIDtgAEuAAFsQAAAAEA"
+      + "DAAAAA4AAwAAAAQACAAFAAsABgAIAA4ACgABAAsAAAAlAAIAAAAAAAmyAAISBrYABLEAAAABAAwA"
+      + "AAAKAAIAAAAIAAgACQABAA8AAAACABA=");
+
+  private static byte[] DEX_BYTES = Base64.getDecoder().decode(
+      "ZGV4CjAzNQARmtFTPdWXebnrTNy5b71tEiJKC96qIPXAAwAAcAAAAHhWNBIAAAAAAAAAABQDAAAQ"
+      + "AAAAcAAAAAYAAACwAAAAAgAAAMgAAAABAAAA4AAAAAUAAADoAAAAAQAAABABAACQAgAAMAEAAKYB"
+      + "AACuAQAAxwEAAOwBAAAAAgAAFwIAACsCAAA/AgAAUwIAAGMCAABmAgAAagIAAG8CAAB4AgAAgAIA"
+      + "AIcCAAADAAAABAAAAAUAAAAGAAAABwAAAAkAAAAJAAAABQAAAAAAAAAKAAAABQAAAKABAAAEAAEA"
+      + "CwAAAAAAAAAAAAAAAAAAAA0AAAAAAAAADgAAAAEAAQAMAAAAAgAAAAAAAAAAAAAAAQAAAAIAAAAA"
+      + "AAAACAAAAAAAAAD+AgAAAAAAAAEAAQABAAAAjgEAAAQAAABwEAQAAAAOAAIAAAACAAAAkgEAAAgA"
+      + "AABiAAAAGgEBAG4gAwAQAA4AAgAAAAIAAACXAQAACwAAAGIAAAAaAQIAbiADABAAcQABAAAADgAC"
+      + "AA4ACAAOeAAEAA54PAAAAAABAAAAAwAGPGluaXQ+ABdHb29kYnllIGZyb20gVGVzdENsYXNzIQAj"
+      + "SGVsbG8gZnJvbSBUZXN0Q2xhc3Mgc2F5SGkgZnVuY3Rpb24AEkxmb29iYXIvVGVzdENsYXNzOwAV"
+      + "TGphdmEvaW8vUHJpbnRTdHJlYW07ABJMamF2YS9sYW5nL09iamVjdDsAEkxqYXZhL2xhbmcvU3Ry"
+      + "aW5nOwASTGphdmEvbGFuZy9TeXN0ZW07AA5UZXN0Q2xhc3MuamF2YQABVgACVkwAA291dAAHcHJp"
+      + "bnRsbgAGc2F5QnllAAVzYXlIaQB1fn5EOHsiY29tcGlsYXRpb24tbW9kZSI6ImRlYnVnIiwibWlu"
+      + "LWFwaSI6MSwic2hhLTEiOiJkMzI4MmI4ZjU0N2MyMzRjNGU0YzkzMDljMzZjNzk1YTI5ODU2ZWFi"
+      + "IiwidmVyc2lvbiI6IjEuNi4xLWRldiJ9AAAAAwAAgYAEsAIBCMgCAQnoAgAAAAAOAAAAAAAAAAEA"
+      + "AAAAAAAAAQAAABAAAABwAAAAAgAAAAYAAACwAAAAAwAAAAIAAADIAAAABAAAAAEAAADgAAAABQAA"
+      + "AAUAAADoAAAABgAAAAEAAAAQAQAAASAAAAMAAAAwAQAAAyAAAAMAAACOAQAAARAAAAEAAACgAQAA"
+      + "AiAAABAAAACmAQAAACAAAAEAAAD+AgAAAxAAAAEAAAAQAwAAABAAAAEAAAAUAwAA");
+  /**
+   * base64 encoded class/dex file for
+   * package foobar;
+   * public class TestClass {
+   *   public static void sayHi() {
+   *    System.out.println("Hello again from TestClass sayHi function");
+   *    NewClass.sayHi();
+   *   }
+   *   static void sayBye() {
+   *    System.out.println("Goodbye again from TestClass!");
+   *   }
+   * }
+   */
+  private static byte[] REDEF_CLASS_BYTES = Base64.getDecoder().decode(
+      "yv66vgAAADUAIwoACAARCQASABMIABQKABUAFgoAFwAYCAAZBwAaBwAbAQAGPGluaXQ+AQADKClW"
+      + "AQAEQ29kZQEAD0xpbmVOdW1iZXJUYWJsZQEABXNheUhpAQAGc2F5QnllAQAKU291cmNlRmlsZQEA"
+      + "DlRlc3RDbGFzcy5qYXZhDAAJAAoHABwMAB0AHgEAKUhlbGxvIGFnYWluIGZyb20gVGVzdENsYXNz"
+      + "IHNheUhpIGZ1bmN0aW9uBwAfDAAgACEHACIMAA0ACgEAHUdvb2RieWUgYWdhaW4gZnJvbSBUZXN0"
+      + "Q2xhc3MhAQAQZm9vYmFyL1Rlc3RDbGFzcwEAEGphdmEvbGFuZy9PYmplY3QBABBqYXZhL2xhbmcv"
+      + "U3lzdGVtAQADb3V0AQAVTGphdmEvaW8vUHJpbnRTdHJlYW07AQATamF2YS9pby9QcmludFN0cmVh"
+      + "bQEAB3ByaW50bG4BABUoTGphdmEvbGFuZy9TdHJpbmc7KVYBAA9mb29iYXIvTmV3Q2xhc3MAIQAH"
+      + "AAgAAAAAAAMAAQAJAAoAAQALAAAAHQABAAEAAAAFKrcAAbEAAAABAAwAAAAGAAEAAAACAAkADQAK"
+      + "AAEACwAAACwAAgAAAAAADLIAAhIDtgAEuAAFsQAAAAEADAAAAA4AAwAAAAQACAAFAAsABgAIAA4A"
+      + "CgABAAsAAAAlAAIAAAAAAAmyAAISBrYABLEAAAABAAwAAAAKAAIAAAAIAAgACQABAA8AAAACABA=");
+
+  private static byte[] REDEF_DEX_BYTES = Base64.getDecoder().decode(
+      "ZGV4CjAzNQA2plEeYRH4vl6wJgnAZOVcZ537QN9NXB3wAwAAcAAAAHhWNBIAAAAAAAAAAEQDAAAR"
+      + "AAAAcAAAAAcAAAC0AAAAAgAAANAAAAABAAAA6AAAAAYAAADwAAAAAQAAACABAACwAgAAQAEAALYB"
+      + "AAC+AQAA3QEAAAgCAAAbAgAALwIAAEYCAABaAgAAbgIAAIICAACSAgAAlQIAAJkCAACeAgAApwIA"
+      + "AK8CAAC2AgAAAwAAAAQAAAAFAAAABgAAAAcAAAAIAAAACgAAAAoAAAAGAAAAAAAAAAsAAAAGAAAA"
+      + "sAEAAAUAAgAMAAAAAAAAAA8AAAABAAAAAAAAAAEAAAAOAAAAAQAAAA8AAAACAAEADQAAAAMAAAAA"
+      + "AAAAAQAAAAEAAAADAAAAAAAAAAkAAAAAAAAALQMAAAAAAAABAAEAAQAAAJ4BAAAEAAAAcBAFAAAA"
+      + "DgACAAAAAgAAAKIBAAAIAAAAYgAAABoBAQBuIAQAEAAOAAIAAAACAAAApwEAAAsAAABiAAAAGgEC"
+      + "AG4gBAAQAHEAAAAAAA4AAgAOAAgADngABAAOeDwAAAAAAQAAAAQABjxpbml0PgAdR29vZGJ5ZSBh"
+      + "Z2FpbiBmcm9tIFRlc3RDbGFzcyEAKUhlbGxvIGFnYWluIGZyb20gVGVzdENsYXNzIHNheUhpIGZ1"
+      + "bmN0aW9uABFMZm9vYmFyL05ld0NsYXNzOwASTGZvb2Jhci9UZXN0Q2xhc3M7ABVMamF2YS9pby9Q"
+      + "cmludFN0cmVhbTsAEkxqYXZhL2xhbmcvT2JqZWN0OwASTGphdmEvbGFuZy9TdHJpbmc7ABJMamF2"
+      + "YS9sYW5nL1N5c3RlbTsADlRlc3RDbGFzcy5qYXZhAAFWAAJWTAADb3V0AAdwcmludGxuAAZzYXlC"
+      + "eWUABXNheUhpAHV+fkQ4eyJjb21waWxhdGlvbi1tb2RlIjoiZGVidWciLCJtaW4tYXBpIjoxLCJz"
+      + "aGEtMSI6ImQzMjgyYjhmNTQ3YzIzNGM0ZTRjOTMwOWMzNmM3OTVhMjk4NTZlYWIiLCJ2ZXJzaW9u"
+      + "IjoiMS42LjEtZGV2In0AAAADAAGBgATAAgEI2AIBCfgCAAAAAAAOAAAAAAAAAAEAAAAAAAAAAQAA"
+      + "ABEAAABwAAAAAgAAAAcAAAC0AAAAAwAAAAIAAADQAAAABAAAAAEAAADoAAAABQAAAAYAAADwAAAA"
+      + "BgAAAAEAAAAgAQAAASAAAAMAAABAAQAAAyAAAAMAAACeAQAAARAAAAEAAACwAQAAAiAAABEAAAC2"
+      + "AQAAACAAAAEAAAAtAwAAAxAAAAEAAABAAwAAABAAAAEAAABEAwAA");
+
+  public static void SafePrintCause(Throwable t) {
+    StackTraceElement cause = t.getStackTrace()[0];
+    System.out.println(" --- " + t.getClass().getName() + " At " + cause.getClassName() + "." +
+                       cause.getMethodName() + "(" + cause.getFileName() + ":" +
+                       cause.getLineNumber() + ")");
+  }
+
+  public static void run() throws Exception {
+    System.out.println(" - Run while adding new referenced class.");
+    try {
+      run(true);
+    } catch (Exception e) {
+      // Unfortunately art and RI have different messages here so just return the type.
+      System.out.println(" -- Exception caught when running test with new class added! " +
+                         e.getCause().getClass().getName());
+      SafePrintCause(e.getCause());
+    }
+    System.out.println(" - Run without adding new referenced class.");
+    try {
+      run(false);
+    } catch (Exception e) {
+      // Unfortunately art and RI have different messages here so just return the type.
+      System.out.println(" -- Exception caught when running test without new class added! " +
+                         e.getCause().getClass().getName());
+      SafePrintCause(e.getCause());
+    }
+  }
+
+  public static void run(boolean add_new) throws Exception {
+    ClassLoader cl = getClassLoader();
+    Class<?> target = cl.loadClass(TEST_CLASS_NAME);
+    Method sayHi = target.getDeclaredMethod("sayHi");
+    System.out.println(" -- Running sayHi before redefinition");
+    sayHi.invoke(null);
+    if (add_new) {
+      System.out.println(" -- Adding NewClass to classloader!");
+      addToClassLoader(cl, NEW_CLASS_BYTES, NEW_DEX_BYTES);
+    }
+    System.out.println(" -- Redefine the TestClass");
+    Redefinition.doCommonClassRedefinition(target, REDEF_CLASS_BYTES, REDEF_DEX_BYTES);
+    System.out.println(" -- call TestClass again, now with NewClass refs");
+    sayHi.invoke(null);
+  }
+
+  public static class ExtensibleClassLoader extends ClassLoader {
+    private byte[] new_class = null;
+    public ExtensibleClassLoader() {
+      super(ExtensibleClassLoader.class.getClassLoader());
+    }
+
+    public void addSingleClass(byte[] bb) {
+      new_class = bb;
+    }
+
+    protected Class<?> findClass(String name) throws ClassNotFoundException {
+      if (name.equals(TEST_CLASS_NAME)) {
+        return this.defineClass(TEST_CLASS_NAME, CLASS_BYTES, 0, CLASS_BYTES.length);
+      }
+      if (name.equals(NEW_CLASS_NAME) && new_class != null) {
+        return this.defineClass(name, new_class, 0, new_class.length);
+      } else {
+        return super.findClass(name);
+      }
+    }
+  }
+
+  public static ClassLoader getClassLoader() throws Exception {
+    if (!IS_ART) {
+      return new ExtensibleClassLoader();
+    } else {
+      Class<?> class_loader_class = Class.forName("dalvik.system.InMemoryDexClassLoader");
+      Constructor<?> ctor = class_loader_class.getConstructor(ByteBuffer.class, ClassLoader.class);
+      return (ClassLoader)ctor.newInstance(ByteBuffer.wrap(DEX_BYTES),
+                                           Test1963.class.getClassLoader());
+    }
+  }
+
+  public static void addToClassLoader(ClassLoader cl, byte[] class_bytes, byte[] dex_bytes) {
+    if (IS_ART) {
+      addToClassLoaderNative(cl, ByteBuffer.allocateDirect(dex_bytes.length).put(dex_bytes));
+    } else {
+      ((ExtensibleClassLoader)cl).addSingleClass(class_bytes);
+    }
+  }
+
+  public static native void addToClassLoaderNative(ClassLoader loader, ByteBuffer buff);
+}
diff --git a/test/1964-add-to-dex-classloader-file/add_to_loader.cc b/test/1964-add-to-dex-classloader-file/add_to_loader.cc
new file mode 100644
index 0000000..9fbea97
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/add_to_loader.cc
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <atomic>
+
+#include "jvmti.h"
+
+// Test infrastructure
+#include "jvmti_helper.h"
+#include "scoped_local_ref.h"
+#include "test_env.h"
+
+namespace art {
+namespace Test1964AddToDexClassLoader {
+
+using AddToDexClassLoader = jvmtiError (*)(jvmtiEnv* env,
+                                                   jobject loader,
+                                                   const char* segment);
+
+template <typename T> static void Dealloc(T* t) {
+  jvmti_env->Deallocate(reinterpret_cast<unsigned char*>(t));
+}
+
+template <typename T, typename... Rest> static void Dealloc(T* t, Rest... rs) {
+  Dealloc(t);
+  Dealloc(rs...);
+}
+static void DeallocParams(jvmtiParamInfo* params, jint n_params) {
+  for (jint i = 0; i < n_params; i++) {
+    Dealloc(params[i].name);
+  }
+}
+
+AddToDexClassLoader GetAddFunction(JNIEnv* env) {
+  // Get the extensions.
+  jint n_ext = 0;
+  jvmtiExtensionFunctionInfo* infos = nullptr;
+  if (JvmtiErrorToException(env, jvmti_env, jvmti_env->GetExtensionFunctions(&n_ext, &infos))) {
+    return nullptr;
+  }
+  AddToDexClassLoader result = nullptr;
+  for (jint i = 0; i < n_ext; i++) {
+    jvmtiExtensionFunctionInfo* cur_info = &infos[i];
+    if (strcmp("com.android.art.classloader.add_to_dex_class_loader", cur_info->id) ==
+        0) {
+      result = reinterpret_cast<AddToDexClassLoader>(cur_info->func);
+    }
+    // Cleanup the cur_info
+    DeallocParams(cur_info->params, cur_info->param_count);
+    Dealloc(cur_info->id, cur_info->short_description, cur_info->params, cur_info->errors);
+  }
+  // Cleanup the array.
+  Dealloc(infos);
+  return result;
+}
+
+extern "C" JNIEXPORT void JNICALL Java_Main_addToClassLoaderNative(JNIEnv* env,
+                                                                           jclass,
+                                                                           jobject loader,
+                                                                           jstring segment) {
+  AddToDexClassLoader add_func = GetAddFunction(env);
+  if (add_func == nullptr) {
+    env->ThrowNew(env->FindClass("java/lang/RuntimeError"), "Failed to find extension function");
+    return;
+  }
+  const char* chars = env->GetStringUTFChars(segment, nullptr);
+  JvmtiErrorToException(
+      env,
+      jvmti_env,
+      add_func(jvmti_env,
+               loader,
+               chars));
+  env->ReleaseStringUTFChars(segment, chars);
+}
+
+}  // namespace Test1964AddToDexClassLoader
+}  // namespace art
diff --git a/test/1964-add-to-dex-classloader-file/expected.txt b/test/1964-add-to-dex-classloader-file/expected.txt
new file mode 100644
index 0000000..58b86ef
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/expected.txt
@@ -0,0 +1,23 @@
+ - Run while adding new referenced class.
+ -- Running sayHi before redefinition
+Hello from TestClass sayHi function
+Goodbye from TestClass!
+ -- Adding NewClass to classloader!
+ -- Redefine the TestClass
+ -- call TestClass again, now with NewClass refs
+Hello again from TestClass sayHi function
+Hello from NewClass sayHi function
+Nearby stack:
+	private static native art.StackTrace$StackFrameData[] art.StackTrace.nativeGetStackTrace(java.lang.Thread)(line: -1)
+	public static art.StackTrace$StackFrameData[] art.StackTrace.GetStackTrace(java.lang.Thread)(line: 61)
+	static void foobar.NewClass.sayHi() throws java.lang.Exception(line: 27)
+	public static void foobar.TestClass.sayHi()(line: 5)
+ - Run without adding new referenced class.
+ -- Running sayHi before redefinition
+Hello from TestClass sayHi function
+Goodbye from TestClass!
+ -- Redefine the TestClass
+ -- call TestClass again, now with NewClass refs
+Hello again from TestClass sayHi function
+ -- Exception caught when running test without new class added! java.lang.NoClassDefFoundError
+ --- java.lang.NoClassDefFoundError At foobar.TestClass.sayHi(TestClass.java:5)
diff --git a/test/1964-add-to-dex-classloader-file/info.txt b/test/1964-add-to-dex-classloader-file/info.txt
new file mode 100644
index 0000000..48df982
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/info.txt
@@ -0,0 +1 @@
+Tests we can add dex-file buffers to an existing classloader and the old classes can see them.
\ No newline at end of file
diff --git a/test/1964-add-to-dex-classloader-file/run b/test/1964-add-to-dex-classloader-file/run
new file mode 100755
index 0000000..c6e62ae
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/run
@@ -0,0 +1,17 @@
+#!/bin/bash
+#
+# Copyright 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+./default-run "$@" --jvmti
diff --git a/test/1964-add-to-dex-classloader-file/src-ex/foobar/NewClass.java b/test/1964-add-to-dex-classloader-file/src-ex/foobar/NewClass.java
new file mode 100644
index 0000000..a27d5d3
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/src-ex/foobar/NewClass.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package foobar;
+import art.Breakpoint;
+import art.StackTrace;
+
+public class NewClass {
+  static void sayHi() throws Exception {
+    System.out.println("Hello from NewClass sayHi function");
+    // Doing this would be nice but it would make compiling the test more tricky. Just use
+    // reflection and check the classloader is the same.
+    // TestClass.sayBye();
+    StackTrace.StackFrameData[] stack = StackTrace.GetStackTrace(Thread.currentThread());
+    StackTrace.StackFrameData caller = null;
+    System.out.println("Nearby stack:");
+    for (StackTrace.StackFrameData sfd : stack) {
+      String caller_name = sfd.method.getDeclaringClass().getName();
+      if (caller_name.startsWith("art.") || caller_name.startsWith("foobar.")) {
+        System.out.println("\t" + sfd.method + "(line: " +
+                           Breakpoint.locationToLine(sfd.method, sfd.current_location) + ")");
+        caller = sfd;
+      } else {
+        break;
+      }
+    }
+    if (NewClass.class.getClassLoader() != caller.method.getDeclaringClass().getClassLoader()) {
+      System.out.println("Different classloader for TestClass and my class.");
+    }
+  }
+}
\ No newline at end of file
diff --git a/test/1964-add-to-dex-classloader-file/src/Main.java b/test/1964-add-to-dex-classloader-file/src/Main.java
new file mode 100644
index 0000000..2293d42
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/src/Main.java
@@ -0,0 +1,210 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import art.Redefinition;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Base64;
+
+public class Main {
+  private static String TEST_NAME = "1964-add-to-dex-classloader-file";
+  private static boolean IS_ART = System.getProperty("java.vm.name").equals("Dalvik");
+
+  private static String TEST_CLASS_NAME = "foobar.TestClass";
+  private static String NEW_CLASS_NAME = "foobar.NewClass";
+
+  /**
+   * base64 encoded class/dex file for
+   * package foobar;
+   * public class TestClass {
+   *   public static void sayHi() {
+   *    System.out.println("Hello again from TestClass sayHi function");
+   *    TestClass.sayBye();
+   *   }
+   *   static void sayBye() {
+   *    System.out.println("Goodbye from TestClass!");
+   *   }
+   * }
+   */
+  private static byte[] CLASS_BYTES = Base64.getDecoder().decode(
+      "yv66vgAAADUAIQoACAARCQASABMIABQKABUAFgoABwAXCAAYBwAZBwAaAQAGPGluaXQ+AQADKClW"
+      + "AQAEQ29kZQEAD0xpbmVOdW1iZXJUYWJsZQEABXNheUhpAQAGc2F5QnllAQAKU291cmNlRmlsZQEA"
+      + "DlRlc3RDbGFzcy5qYXZhDAAJAAoHABsMABwAHQEAI0hlbGxvIGZyb20gVGVzdENsYXNzIHNheUhp"
+      + "IGZ1bmN0aW9uBwAeDAAfACAMAA4ACgEAF0dvb2RieWUgZnJvbSBUZXN0Q2xhc3MhAQAQZm9vYmFy"
+      + "L1Rlc3RDbGFzcwEAEGphdmEvbGFuZy9PYmplY3QBABBqYXZhL2xhbmcvU3lzdGVtAQADb3V0AQAV"
+      + "TGphdmEvaW8vUHJpbnRTdHJlYW07AQATamF2YS9pby9QcmludFN0cmVhbQEAB3ByaW50bG4BABUo"
+      + "TGphdmEvbGFuZy9TdHJpbmc7KVYAIQAHAAgAAAAAAAMAAQAJAAoAAQALAAAAHQABAAEAAAAFKrcA"
+      + "AbEAAAABAAwAAAAGAAEAAAACAAkADQAKAAEACwAAACwAAgAAAAAADLIAAhIDtgAEuAAFsQAAAAEA"
+      + "DAAAAA4AAwAAAAQACAAFAAsABgAIAA4ACgABAAsAAAAlAAIAAAAAAAmyAAISBrYABLEAAAABAAwA"
+      + "AAAKAAIAAAAIAAgACQABAA8AAAACABA=");
+
+  private static byte[] DEX_BYTES = Base64.getDecoder().decode(
+      "ZGV4CjAzNQARmtFTPdWXebnrTNy5b71tEiJKC96qIPXAAwAAcAAAAHhWNBIAAAAAAAAAABQDAAAQ"
+      + "AAAAcAAAAAYAAACwAAAAAgAAAMgAAAABAAAA4AAAAAUAAADoAAAAAQAAABABAACQAgAAMAEAAKYB"
+      + "AACuAQAAxwEAAOwBAAAAAgAAFwIAACsCAAA/AgAAUwIAAGMCAABmAgAAagIAAG8CAAB4AgAAgAIA"
+      + "AIcCAAADAAAABAAAAAUAAAAGAAAABwAAAAkAAAAJAAAABQAAAAAAAAAKAAAABQAAAKABAAAEAAEA"
+      + "CwAAAAAAAAAAAAAAAAAAAA0AAAAAAAAADgAAAAEAAQAMAAAAAgAAAAAAAAAAAAAAAQAAAAIAAAAA"
+      + "AAAACAAAAAAAAAD+AgAAAAAAAAEAAQABAAAAjgEAAAQAAABwEAQAAAAOAAIAAAACAAAAkgEAAAgA"
+      + "AABiAAAAGgEBAG4gAwAQAA4AAgAAAAIAAACXAQAACwAAAGIAAAAaAQIAbiADABAAcQABAAAADgAC"
+      + "AA4ACAAOeAAEAA54PAAAAAABAAAAAwAGPGluaXQ+ABdHb29kYnllIGZyb20gVGVzdENsYXNzIQAj"
+      + "SGVsbG8gZnJvbSBUZXN0Q2xhc3Mgc2F5SGkgZnVuY3Rpb24AEkxmb29iYXIvVGVzdENsYXNzOwAV"
+      + "TGphdmEvaW8vUHJpbnRTdHJlYW07ABJMamF2YS9sYW5nL09iamVjdDsAEkxqYXZhL2xhbmcvU3Ry"
+      + "aW5nOwASTGphdmEvbGFuZy9TeXN0ZW07AA5UZXN0Q2xhc3MuamF2YQABVgACVkwAA291dAAHcHJp"
+      + "bnRsbgAGc2F5QnllAAVzYXlIaQB1fn5EOHsiY29tcGlsYXRpb24tbW9kZSI6ImRlYnVnIiwibWlu"
+      + "LWFwaSI6MSwic2hhLTEiOiJkMzI4MmI4ZjU0N2MyMzRjNGU0YzkzMDljMzZjNzk1YTI5ODU2ZWFi"
+      + "IiwidmVyc2lvbiI6IjEuNi4xLWRldiJ9AAAAAwAAgYAEsAIBCMgCAQnoAgAAAAAOAAAAAAAAAAEA"
+      + "AAAAAAAAAQAAABAAAABwAAAAAgAAAAYAAACwAAAAAwAAAAIAAADIAAAABAAAAAEAAADgAAAABQAA"
+      + "AAUAAADoAAAABgAAAAEAAAAQAQAAASAAAAMAAAAwAQAAAyAAAAMAAACOAQAAARAAAAEAAACgAQAA"
+      + "AiAAABAAAACmAQAAACAAAAEAAAD+AgAAAxAAAAEAAAAQAwAAABAAAAEAAAAUAwAA");
+  /**
+   * base64 encoded class/dex file for
+   * package foobar;
+   * public class TestClass {
+   *   public static void sayHi() {
+   *    System.out.println("Hello again from TestClass sayHi function");
+   *    NewClass.sayHi();
+   *   }
+   *   static void sayBye() {
+   *    System.out.println("Goodbye again from TestClass!");
+   *   }
+   * }
+   */
+  private static byte[] REDEF_CLASS_BYTES = Base64.getDecoder().decode(
+      "yv66vgAAADUAIwoACAARCQASABMIABQKABUAFgoAFwAYCAAZBwAaBwAbAQAGPGluaXQ+AQADKClW"
+      + "AQAEQ29kZQEAD0xpbmVOdW1iZXJUYWJsZQEABXNheUhpAQAGc2F5QnllAQAKU291cmNlRmlsZQEA"
+      + "DlRlc3RDbGFzcy5qYXZhDAAJAAoHABwMAB0AHgEAKUhlbGxvIGFnYWluIGZyb20gVGVzdENsYXNz"
+      + "IHNheUhpIGZ1bmN0aW9uBwAfDAAgACEHACIMAA0ACgEAHUdvb2RieWUgYWdhaW4gZnJvbSBUZXN0"
+      + "Q2xhc3MhAQAQZm9vYmFyL1Rlc3RDbGFzcwEAEGphdmEvbGFuZy9PYmplY3QBABBqYXZhL2xhbmcv"
+      + "U3lzdGVtAQADb3V0AQAVTGphdmEvaW8vUHJpbnRTdHJlYW07AQATamF2YS9pby9QcmludFN0cmVh"
+      + "bQEAB3ByaW50bG4BABUoTGphdmEvbGFuZy9TdHJpbmc7KVYBAA9mb29iYXIvTmV3Q2xhc3MAIQAH"
+      + "AAgAAAAAAAMAAQAJAAoAAQALAAAAHQABAAEAAAAFKrcAAbEAAAABAAwAAAAGAAEAAAACAAkADQAK"
+      + "AAEACwAAACwAAgAAAAAADLIAAhIDtgAEuAAFsQAAAAEADAAAAA4AAwAAAAQACAAFAAsABgAIAA4A"
+      + "CgABAAsAAAAlAAIAAAAAAAmyAAISBrYABLEAAAABAAwAAAAKAAIAAAAIAAgACQABAA8AAAACABA=");
+
+  private static byte[] REDEF_DEX_BYTES = Base64.getDecoder().decode(
+      "ZGV4CjAzNQA2plEeYRH4vl6wJgnAZOVcZ537QN9NXB3wAwAAcAAAAHhWNBIAAAAAAAAAAEQDAAAR"
+      + "AAAAcAAAAAcAAAC0AAAAAgAAANAAAAABAAAA6AAAAAYAAADwAAAAAQAAACABAACwAgAAQAEAALYB"
+      + "AAC+AQAA3QEAAAgCAAAbAgAALwIAAEYCAABaAgAAbgIAAIICAACSAgAAlQIAAJkCAACeAgAApwIA"
+      + "AK8CAAC2AgAAAwAAAAQAAAAFAAAABgAAAAcAAAAIAAAACgAAAAoAAAAGAAAAAAAAAAsAAAAGAAAA"
+      + "sAEAAAUAAgAMAAAAAAAAAA8AAAABAAAAAAAAAAEAAAAOAAAAAQAAAA8AAAACAAEADQAAAAMAAAAA"
+      + "AAAAAQAAAAEAAAADAAAAAAAAAAkAAAAAAAAALQMAAAAAAAABAAEAAQAAAJ4BAAAEAAAAcBAFAAAA"
+      + "DgACAAAAAgAAAKIBAAAIAAAAYgAAABoBAQBuIAQAEAAOAAIAAAACAAAApwEAAAsAAABiAAAAGgEC"
+      + "AG4gBAAQAHEAAAAAAA4AAgAOAAgADngABAAOeDwAAAAAAQAAAAQABjxpbml0PgAdR29vZGJ5ZSBh"
+      + "Z2FpbiBmcm9tIFRlc3RDbGFzcyEAKUhlbGxvIGFnYWluIGZyb20gVGVzdENsYXNzIHNheUhpIGZ1"
+      + "bmN0aW9uABFMZm9vYmFyL05ld0NsYXNzOwASTGZvb2Jhci9UZXN0Q2xhc3M7ABVMamF2YS9pby9Q"
+      + "cmludFN0cmVhbTsAEkxqYXZhL2xhbmcvT2JqZWN0OwASTGphdmEvbGFuZy9TdHJpbmc7ABJMamF2"
+      + "YS9sYW5nL1N5c3RlbTsADlRlc3RDbGFzcy5qYXZhAAFWAAJWTAADb3V0AAdwcmludGxuAAZzYXlC"
+      + "eWUABXNheUhpAHV+fkQ4eyJjb21waWxhdGlvbi1tb2RlIjoiZGVidWciLCJtaW4tYXBpIjoxLCJz"
+      + "aGEtMSI6ImQzMjgyYjhmNTQ3YzIzNGM0ZTRjOTMwOWMzNmM3OTVhMjk4NTZlYWIiLCJ2ZXJzaW9u"
+      + "IjoiMS42LjEtZGV2In0AAAADAAGBgATAAgEI2AIBCfgCAAAAAAAOAAAAAAAAAAEAAAAAAAAAAQAA"
+      + "ABEAAABwAAAAAgAAAAcAAAC0AAAAAwAAAAIAAADQAAAABAAAAAEAAADoAAAABQAAAAYAAADwAAAA"
+      + "BgAAAAEAAAAgAQAAASAAAAMAAABAAQAAAyAAAAMAAACeAQAAARAAAAEAAACwAQAAAiAAABEAAAC2"
+      + "AQAAACAAAAEAAAAtAwAAAxAAAAEAAABAAwAAABAAAAEAAABEAwAA");
+
+  public static void SafePrintCause(Throwable t) {
+    StackTraceElement cause = t.getStackTrace()[0];
+    System.out.println(" --- " + t.getClass().getName() + " At " + cause.getClassName() + "." +
+                       cause.getMethodName() + "(" + cause.getFileName() + ":" +
+                       cause.getLineNumber() + ")");
+  }
+
+  public static void run() throws Exception {
+    System.out.println(" - Run while adding new referenced class.");
+    try {
+      run(true);
+    } catch (Exception e) {
+      // Unfortunately art and RI have different messages here so just return the type.
+      System.out.println(" -- Exception caught when running test with new class added! " +
+                         e.getCause().getClass().getName());
+      SafePrintCause(e.getCause());
+      System.out.println(e);
+      e.printStackTrace();
+    }
+    System.out.println(" - Run without adding new referenced class.");
+    try {
+      run(false);
+    } catch (Exception e) {
+      // Unfortunately art and RI have different messages here so just return the type.
+      System.out.println(" -- Exception caught when running test without new class added! " +
+                         e.getCause().getClass().getName());
+      SafePrintCause(e.getCause());
+    }
+  }
+
+  public static void run(boolean add_new) throws Exception {
+    ClassLoader cl = getClassLoader();
+    Class<?> target = cl.loadClass(TEST_CLASS_NAME);
+    Method sayHi = target.getDeclaredMethod("sayHi");
+    System.out.println(" -- Running sayHi before redefinition");
+    sayHi.invoke(null);
+    if (add_new) {
+      System.out.println(" -- Adding NewClass to classloader!");
+      addToClassLoader(cl);
+    }
+    System.out.println(" -- Redefine the TestClass");
+    Redefinition.doCommonClassRedefinition(target, REDEF_CLASS_BYTES, REDEF_DEX_BYTES);
+    System.out.println(" -- call TestClass again, now with NewClass refs");
+    sayHi.invoke(null);
+  }
+
+  public static class ExtensibleClassLoader extends URLClassLoader {
+    public ExtensibleClassLoader() {
+      // Initially we don't have any URLs
+      super(new URL[] {}, ExtensibleClassLoader.class.getClassLoader());
+    }
+
+    public void addSingleUrl(String file) throws Exception {
+      this.addURL(new URL("file://" + file));
+    }
+
+    protected Class<?> findClass(String name) throws ClassNotFoundException {
+      // Just define the TestClass without other jars.
+      if (name.equals(TEST_CLASS_NAME)) {
+        return this.defineClass(TEST_CLASS_NAME, CLASS_BYTES, 0, CLASS_BYTES.length);
+      } else {
+        return super.findClass(name);
+      }
+    }
+  }
+
+  public static ClassLoader getClassLoader() throws Exception {
+    if (!IS_ART) {
+      return new ExtensibleClassLoader();
+    } else {
+      Class<?> class_loader_class = Class.forName("dalvik.system.InMemoryDexClassLoader");
+      Constructor<?> ctor = class_loader_class.getConstructor(ByteBuffer.class, ClassLoader.class);
+      return (ClassLoader)ctor.newInstance(ByteBuffer.wrap(DEX_BYTES), Main.class.getClassLoader());
+    }
+  }
+
+  public static void addToClassLoader(ClassLoader cl) throws Exception {
+    if (IS_ART) {
+      addToClassLoaderNative(cl, System.getenv("DEX_LOCATION") + "/" + TEST_NAME + "-ex.jar");
+    } else {
+      ((ExtensibleClassLoader)cl).addSingleUrl(System.getenv("DEX_LOCATION") + "/classes-ex/");
+    }
+  }
+
+  public static native void addToClassLoaderNative(ClassLoader loader, String segment);
+  public static void main(String[] args) throws Exception {
+    run();
+  }
+}
diff --git a/test/1964-add-to-dex-classloader-file/src/art/Breakpoint.java b/test/1964-add-to-dex-classloader-file/src/art/Breakpoint.java
new file mode 120000
index 0000000..3673916
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/src/art/Breakpoint.java
@@ -0,0 +1 @@
+../../../jvmti-common/Breakpoint.java
\ No newline at end of file
diff --git a/test/1964-add-to-dex-classloader-file/src/art/Redefinition.java b/test/1964-add-to-dex-classloader-file/src/art/Redefinition.java
new file mode 120000
index 0000000..81eaf31
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/src/art/Redefinition.java
@@ -0,0 +1 @@
+../../../jvmti-common/Redefinition.java
\ No newline at end of file
diff --git a/test/1964-add-to-dex-classloader-file/src/art/StackTrace.java b/test/1964-add-to-dex-classloader-file/src/art/StackTrace.java
new file mode 120000
index 0000000..e1a08aa
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/src/art/StackTrace.java
@@ -0,0 +1 @@
+../../../jvmti-common/StackTrace.java
\ No newline at end of file
diff --git a/test/1964-add-to-dex-classloader-file/src/art/Suspension.java b/test/1964-add-to-dex-classloader-file/src/art/Suspension.java
new file mode 120000
index 0000000..bcef96f
--- /dev/null
+++ b/test/1964-add-to-dex-classloader-file/src/art/Suspension.java
@@ -0,0 +1 @@
+../../../jvmti-common/Suspension.java
\ No newline at end of file
diff --git a/test/Android.bp b/test/Android.bp
index 5ebca66..7f25a6a 100644
--- a/test/Android.bp
+++ b/test/Android.bp
@@ -294,6 +294,7 @@
         "1953-pop-frame/pop_frame.cc",
         "1957-error-ext/lasterror.cc",
         "1962-multi-thread-events/multi_thread_events.cc",
+        "1963-add-to-dex-classloader-in-memory/add_to_loader.cc",
     ],
     // Use NDK-compatible headers for ctstiagent.
     header_libs: [
@@ -326,6 +327,7 @@
         // "1952-pop-frame-jit/pop_frame.cc",
         "1959-redefine-object-instrument/fake_redef_object.cc",
         "1960-obsolete-jit-multithread-native/native_say_hi.cc",
+        "1964-add-to-dex-classloader-file/add_to_loader.cc",
     ],
     static_libs: [
         "libz",