diff --git a/ReactAndroid/src/main/jni/react/jni/CatalystInstanceImpl.cpp b/ReactAndroid/src/main/jni/react/jni/CatalystInstanceImpl.cpp
index 06a224f457ab50..28de85f7ba2f22 100644
--- a/ReactAndroid/src/main/jni/react/jni/CatalystInstanceImpl.cpp
+++ b/ReactAndroid/src/main/jni/react/jni/CatalystInstanceImpl.cpp
@@ -199,6 +199,8 @@ void CatalystInstanceImpl::jniLoadScriptFromAssets(
       sourceURL,
       loadSynchronously);
     return;
+  } else if (Instance::isIndexedRAMBundle(&script)) {
+    instance_->loadRAMBundleFromString(std::move(script), sourceURL);
   } else {
     instance_->loadScriptFromString(std::move(script), sourceURL, loadSynchronously);
   }
diff --git a/ReactCommon/cxxreact/Instance.cpp b/ReactCommon/cxxreact/Instance.cpp
index ad5069238d6e32..81996813893b92 100644
--- a/ReactCommon/cxxreact/Instance.cpp
+++ b/ReactCommon/cxxreact/Instance.cpp
@@ -108,6 +108,24 @@ bool Instance::isIndexedRAMBundle(const char *sourcePath) {
   return parseTypeFromHeader(header) == ScriptTag::RAMBundle;
 }
 
+bool Instance::isIndexedRAMBundle(std::unique_ptr<const JSBigString>* script) {
+  BundleHeader header;
+  strncpy(reinterpret_cast<char *>(&header), script->get()->c_str(), sizeof(header));
+
+  return parseTypeFromHeader(header) == ScriptTag::RAMBundle;
+}
+
+void Instance::loadRAMBundleFromString(std::unique_ptr<const JSBigString> script, const std::string& sourceURL) {
+  auto bundle = folly::make_unique<JSIndexedRAMBundle>(std::move(script));
+  auto startupScript = bundle->getStartupCode();
+  auto registry = RAMBundleRegistry::singleBundleRegistry(std::move(bundle));
+  loadRAMBundle(
+    std::move(registry),
+    std::move(startupScript),
+    sourceURL,
+    true);
+}
+
 void Instance::loadRAMBundleFromFile(const std::string& sourcePath,
                            const std::string& sourceURL,
                            bool loadSynchronously) {
diff --git a/ReactCommon/cxxreact/Instance.h b/ReactCommon/cxxreact/Instance.h
index b72729660ff601..b129ee7e633287 100644
--- a/ReactCommon/cxxreact/Instance.h
+++ b/ReactCommon/cxxreact/Instance.h
@@ -47,6 +47,8 @@ class RN_EXPORT Instance {
   void loadScriptFromString(std::unique_ptr<const JSBigString> string,
                             std::string sourceURL, bool loadSynchronously);
   static bool isIndexedRAMBundle(const char *sourcePath);
+  static bool isIndexedRAMBundle(std::unique_ptr<const JSBigString>* string);
+  void loadRAMBundleFromString(std::unique_ptr<const JSBigString> script, const std::string& sourceURL);
   void loadRAMBundleFromFile(const std::string& sourcePath,
                              const std::string& sourceURL,
                              bool loadSynchronously);
diff --git a/ReactCommon/cxxreact/JSIndexedRAMBundle.cpp b/ReactCommon/cxxreact/JSIndexedRAMBundle.cpp
index 6c2e7e87c7eb26..65c73a11aef7c5 100644
--- a/ReactCommon/cxxreact/JSIndexedRAMBundle.cpp
+++ b/ReactCommon/cxxreact/JSIndexedRAMBundle.cpp
@@ -6,7 +6,8 @@
 #include "JSIndexedRAMBundle.h"
 
 #include <glog/logging.h>
-
+#include <fstream>
+#include <sstream>
 #include <folly/Memory.h>
 
 namespace facebook {
@@ -18,14 +19,30 @@ std::function<std::unique_ptr<JSModulesUnbundle>(std::string)> JSIndexedRAMBundl
   };
 }
 
-JSIndexedRAMBundle::JSIndexedRAMBundle(const char *sourcePath) :
-    m_bundle (sourcePath, std::ios_base::in) {
+JSIndexedRAMBundle::JSIndexedRAMBundle(const char *sourcePath) {
+  m_bundle = std::make_unique<std::ifstream>(sourcePath, std::ifstream::binary);
   if (!m_bundle) {
     throw std::ios_base::failure(
       folly::to<std::string>("Bundle ", sourcePath,
-                             "cannot be opened: ", m_bundle.rdstate()));
+                             "cannot be opened: ", m_bundle->rdstate()));
   }
+  init();
+}
+
+JSIndexedRAMBundle::JSIndexedRAMBundle(std::unique_ptr<const JSBigString> script) {
+  // tmpStream is needed because m_bundle is std::istream type
+  // which has no member 'write'
+  std::unique_ptr<std::stringstream> tmpStream = std::make_unique<std::stringstream>();
+  tmpStream->write(script->c_str(), script->size());
+  m_bundle = std::move(tmpStream);
+  if (!m_bundle) {
+    throw std::ios_base::failure(
+      folly::to<std::string>("Bundle from string cannot be opened: ", m_bundle->rdstate()));
+  }
+  init();
+}
 
+void JSIndexedRAMBundle::init() {
   // read in magic header, number of entries, and length of the startup section
   uint32_t header[3];
   static_assert(
@@ -78,12 +95,12 @@ std::string JSIndexedRAMBundle::getModuleCode(const uint32_t id) const {
 }
 
 void JSIndexedRAMBundle::readBundle(char *buffer, const std::streamsize bytes) const {
-  if (!m_bundle.read(buffer, bytes)) {
-    if (m_bundle.rdstate() & std::ios::eofbit) {
+  if (!m_bundle->read(buffer, bytes)) {
+    if (m_bundle->rdstate() & std::ios::eofbit) {
       throw std::ios_base::failure("Unexpected end of RAM Bundle file");
     }
     throw std::ios_base::failure(
-      folly::to<std::string>("Error reading RAM Bundle: ", m_bundle.rdstate()));
+      folly::to<std::string>("Error reading RAM Bundle: ", m_bundle->rdstate()));
   }
 }
 
@@ -92,9 +109,9 @@ void JSIndexedRAMBundle::readBundle(
     const std::streamsize bytes,
     const std::ifstream::pos_type position) const {
 
-  if (!m_bundle.seekg(position)) {
+  if (!m_bundle->seekg(position)) {
     throw std::ios_base::failure(
-      folly::to<std::string>("Error reading RAM Bundle: ", m_bundle.rdstate()));
+      folly::to<std::string>("Error reading RAM Bundle: ", m_bundle->rdstate()));
   }
   readBundle(buffer, bytes);
 }
diff --git a/ReactCommon/cxxreact/JSIndexedRAMBundle.h b/ReactCommon/cxxreact/JSIndexedRAMBundle.h
index be6b27f7a84576..2f2db3b708fc26 100644
--- a/ReactCommon/cxxreact/JSIndexedRAMBundle.h
+++ b/ReactCommon/cxxreact/JSIndexedRAMBundle.h
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <fstream>
+#include <istream>
 #include <memory>
 
 #include <cxxreact/JSBigString.h>
@@ -24,6 +24,7 @@ class RN_EXPORT JSIndexedRAMBundle : public JSModulesUnbundle {
 
   // Throws std::runtime_error on failure.
   JSIndexedRAMBundle(const char *sourceURL);
+  JSIndexedRAMBundle(std::unique_ptr<const JSBigString> script);
 
   // Throws std::runtime_error on failure.
   std::unique_ptr<const JSBigString> getStartupCode();
@@ -51,14 +52,15 @@ class RN_EXPORT JSIndexedRAMBundle : public JSModulesUnbundle {
     }
   };
 
+  void init();
   std::string getModuleCode(const uint32_t id) const;
   void readBundle(char *buffer, const std::streamsize bytes) const;
   void readBundle(
     char *buffer, const
     std::streamsize bytes,
-    const std::ifstream::pos_type position) const;
+    const std::istream::pos_type position) const;
 
-  mutable std::ifstream m_bundle;
+  mutable std::unique_ptr<std::istream> m_bundle;
   ModuleTable m_table;
   size_t m_baseOffset;
   std::unique_ptr<JSBigBufferString> m_startupCode;