diff --git a/ReactCommon/hermes/inspector/chrome/Connection.cpp b/ReactCommon/hermes/inspector/chrome/Connection.cpp
index 2fa87b5386452c..e554f654dcbf51 100644
--- a/ReactCommon/hermes/inspector/chrome/Connection.cpp
+++ b/ReactCommon/hermes/inspector/chrome/Connection.cpp
@@ -103,6 +103,7 @@ class Connection::Impl : public inspector::InspectorObserver,
   void handle(const m::heapProfiler::GetHeapObjectIdRequest &req) override;
   void handle(const m::runtime::CallFunctionOnRequest &req) override;
   void handle(const m::runtime::EvaluateRequest &req) override;
+  void handle(const m::runtime::GetHeapUsageRequest &req) override;
   void handle(const m::runtime::GetPropertiesRequest &req) override;
   void handle(const m::runtime::RunIfWaitingForDebuggerRequest &req) override;
 
@@ -1348,6 +1349,23 @@ Connection::Impl::makePropsFromValue(
   return result;
 }
 
+void Connection::Impl::handle(const m::runtime::GetHeapUsageRequest &req) {
+  auto resp = std::make_shared<m::runtime::GetHeapUsageResponse>();
+  resp->id = req.id;
+
+  inspector_
+      ->executeIfEnabled(
+          "Runtime.getHeapUsage",
+          [this, req, resp](const debugger::ProgramState &state) {
+            auto heapInfo = getRuntime().instrumentation().getHeapInfo(false);
+            resp->usedSize = heapInfo["hermes_allocatedBytes"];
+            resp->totalSize = heapInfo["hermes_heapSize"];
+          })
+      .via(executor_.get())
+      .thenValue([this, resp](auto &&) { sendResponseToClient(*resp); })
+      .thenError<std::exception>(sendErrorToClient(req.id));
+}
+
 void Connection::Impl::handle(const m::runtime::GetPropertiesRequest &req) {
   auto resp = std::make_shared<m::runtime::GetPropertiesResponse>();
   resp->id = req.id;
diff --git a/ReactCommon/hermes/inspector/chrome/MessageTypes.cpp b/ReactCommon/hermes/inspector/chrome/MessageTypes.cpp
index 170f90593b9281..b7cab9c550e8dc 100644
--- a/ReactCommon/hermes/inspector/chrome/MessageTypes.cpp
+++ b/ReactCommon/hermes/inspector/chrome/MessageTypes.cpp
@@ -62,6 +62,7 @@ std::unique_ptr<Request> Request::fromJsonThrowOnError(const std::string &str) {
        makeUnique<heapProfiler::TakeHeapSnapshotRequest>},
       {"Runtime.callFunctionOn", makeUnique<runtime::CallFunctionOnRequest>},
       {"Runtime.evaluate", makeUnique<runtime::EvaluateRequest>},
+      {"Runtime.getHeapUsage", makeUnique<runtime::GetHeapUsageRequest>},
       {"Runtime.getProperties", makeUnique<runtime::GetPropertiesRequest>},
       {"Runtime.runIfWaitingForDebugger",
        makeUnique<runtime::RunIfWaitingForDebuggerRequest>},
@@ -503,12 +504,22 @@ debugger::ResumeRequest::ResumeRequest(const dynamic &obj)
     : Request("Debugger.resume") {
   assign(id, obj, "id");
   assign(method, obj, "method");
+
+  auto it = obj.find("params");
+  if (it != obj.items().end()) {
+    dynamic params = it->second;
+    assign(terminateOnResume, params, "terminateOnResume");
+  }
 }
 
 dynamic debugger::ResumeRequest::toDynamic() const {
+  dynamic params = dynamic::object;
+  put(params, "terminateOnResume", terminateOnResume);
+
   dynamic obj = dynamic::object;
   put(obj, "id", id);
   put(obj, "method", method);
+  put(obj, "params", std::move(params));
   return obj;
 }
 
@@ -817,8 +828,11 @@ heapProfiler::StartSamplingRequest::StartSamplingRequest(const dynamic &obj)
   assign(id, obj, "id");
   assign(method, obj, "method");
 
-  dynamic params = obj.at("params");
-  assign(samplingInterval, params, "samplingInterval");
+  auto it = obj.find("params");
+  if (it != obj.items().end()) {
+    dynamic params = it->second;
+    assign(samplingInterval, params, "samplingInterval");
+  }
 }
 
 dynamic heapProfiler::StartSamplingRequest::toDynamic() const {
@@ -845,8 +859,11 @@ heapProfiler::StartTrackingHeapObjectsRequest::StartTrackingHeapObjectsRequest(
   assign(id, obj, "id");
   assign(method, obj, "method");
 
-  dynamic params = obj.at("params");
-  assign(trackAllocations, params, "trackAllocations");
+  auto it = obj.find("params");
+  if (it != obj.items().end()) {
+    dynamic params = it->second;
+    assign(trackAllocations, params, "trackAllocations");
+  }
 }
 
 dynamic heapProfiler::StartTrackingHeapObjectsRequest::toDynamic() const {
@@ -894,15 +911,20 @@ heapProfiler::StopTrackingHeapObjectsRequest::StopTrackingHeapObjectsRequest(
   assign(id, obj, "id");
   assign(method, obj, "method");
 
-  dynamic params = obj.at("params");
-  assign(reportProgress, params, "reportProgress");
-  assign(treatGlobalObjectsAsRoots, params, "treatGlobalObjectsAsRoots");
+  auto it = obj.find("params");
+  if (it != obj.items().end()) {
+    dynamic params = it->second;
+    assign(reportProgress, params, "reportProgress");
+    assign(treatGlobalObjectsAsRoots, params, "treatGlobalObjectsAsRoots");
+    assign(captureNumericValue, params, "captureNumericValue");
+  }
 }
 
 dynamic heapProfiler::StopTrackingHeapObjectsRequest::toDynamic() const {
   dynamic params = dynamic::object;
   put(params, "reportProgress", reportProgress);
   put(params, "treatGlobalObjectsAsRoots", treatGlobalObjectsAsRoots);
+  put(params, "captureNumericValue", captureNumericValue);
 
   dynamic obj = dynamic::object;
   put(obj, "id", id);
@@ -925,15 +947,20 @@ heapProfiler::TakeHeapSnapshotRequest::TakeHeapSnapshotRequest(
   assign(id, obj, "id");
   assign(method, obj, "method");
 
-  dynamic params = obj.at("params");
-  assign(reportProgress, params, "reportProgress");
-  assign(treatGlobalObjectsAsRoots, params, "treatGlobalObjectsAsRoots");
+  auto it = obj.find("params");
+  if (it != obj.items().end()) {
+    dynamic params = it->second;
+    assign(reportProgress, params, "reportProgress");
+    assign(treatGlobalObjectsAsRoots, params, "treatGlobalObjectsAsRoots");
+    assign(captureNumericValue, params, "captureNumericValue");
+  }
 }
 
 dynamic heapProfiler::TakeHeapSnapshotRequest::toDynamic() const {
   dynamic params = dynamic::object;
   put(params, "reportProgress", reportProgress);
   put(params, "treatGlobalObjectsAsRoots", treatGlobalObjectsAsRoots);
+  put(params, "captureNumericValue", captureNumericValue);
 
   dynamic obj = dynamic::object;
   put(obj, "id", id);
@@ -1030,6 +1057,26 @@ void runtime::EvaluateRequest::accept(RequestHandler &handler) const {
   handler.handle(*this);
 }
 
+runtime::GetHeapUsageRequest::GetHeapUsageRequest()
+    : Request("Runtime.getHeapUsage") {}
+
+runtime::GetHeapUsageRequest::GetHeapUsageRequest(const dynamic &obj)
+    : Request("Runtime.getHeapUsage") {
+  assign(id, obj, "id");
+  assign(method, obj, "method");
+}
+
+dynamic runtime::GetHeapUsageRequest::toDynamic() const {
+  dynamic obj = dynamic::object;
+  put(obj, "id", id);
+  put(obj, "method", method);
+  return obj;
+}
+
+void runtime::GetHeapUsageRequest::accept(RequestHandler &handler) const {
+  handler.handle(*this);
+}
+
 runtime::GetPropertiesRequest::GetPropertiesRequest()
     : Request("Runtime.getProperties") {}
 
@@ -1284,6 +1331,25 @@ dynamic runtime::EvaluateResponse::toDynamic() const {
   return obj;
 }
 
+runtime::GetHeapUsageResponse::GetHeapUsageResponse(const dynamic &obj) {
+  assign(id, obj, "id");
+
+  dynamic res = obj.at("result");
+  assign(usedSize, res, "usedSize");
+  assign(totalSize, res, "totalSize");
+}
+
+dynamic runtime::GetHeapUsageResponse::toDynamic() const {
+  dynamic res = dynamic::object;
+  put(res, "usedSize", usedSize);
+  put(res, "totalSize", totalSize);
+
+  dynamic obj = dynamic::object;
+  put(obj, "id", id);
+  put(obj, "result", std::move(res));
+  return obj;
+}
+
 runtime::GetPropertiesResponse::GetPropertiesResponse(const dynamic &obj) {
   assign(id, obj, "id");
 
diff --git a/ReactCommon/hermes/inspector/chrome/MessageTypes.h b/ReactCommon/hermes/inspector/chrome/MessageTypes.h
index 78468d6fb11db6..10ff9e4ca32c9d 100644
--- a/ReactCommon/hermes/inspector/chrome/MessageTypes.h
+++ b/ReactCommon/hermes/inspector/chrome/MessageTypes.h
@@ -59,6 +59,8 @@ struct ExceptionDetails;
 struct ExecutionContextCreatedNotification;
 struct ExecutionContextDescription;
 using ExecutionContextId = int;
+struct GetHeapUsageRequest;
+struct GetHeapUsageResponse;
 struct GetPropertiesRequest;
 struct GetPropertiesResponse;
 struct InternalPropertyDescriptor;
@@ -127,6 +129,7 @@ struct RequestHandler {
   virtual void handle(const heapProfiler::TakeHeapSnapshotRequest &req) = 0;
   virtual void handle(const runtime::CallFunctionOnRequest &req) = 0;
   virtual void handle(const runtime::EvaluateRequest &req) = 0;
+  virtual void handle(const runtime::GetHeapUsageRequest &req) = 0;
   virtual void handle(const runtime::GetPropertiesRequest &req) = 0;
   virtual void handle(const runtime::RunIfWaitingForDebuggerRequest &req) = 0;
 };
@@ -162,6 +165,7 @@ struct NoopRequestHandler : public RequestHandler {
   void handle(const heapProfiler::TakeHeapSnapshotRequest &req) override {}
   void handle(const runtime::CallFunctionOnRequest &req) override {}
   void handle(const runtime::EvaluateRequest &req) override {}
+  void handle(const runtime::GetHeapUsageRequest &req) override {}
   void handle(const runtime::GetPropertiesRequest &req) override {}
   void handle(const runtime::RunIfWaitingForDebuggerRequest &req) override {}
 };
@@ -400,6 +404,8 @@ struct debugger::ResumeRequest : public Request {
 
   folly::dynamic toDynamic() const override;
   void accept(RequestHandler &handler) const override;
+
+  folly::Optional<bool> terminateOnResume;
 };
 
 struct debugger::SetBreakpointRequest : public Request {
@@ -548,6 +554,7 @@ struct heapProfiler::StopTrackingHeapObjectsRequest : public Request {
 
   folly::Optional<bool> reportProgress;
   folly::Optional<bool> treatGlobalObjectsAsRoots;
+  folly::Optional<bool> captureNumericValue;
 };
 
 struct heapProfiler::TakeHeapSnapshotRequest : public Request {
@@ -559,6 +566,7 @@ struct heapProfiler::TakeHeapSnapshotRequest : public Request {
 
   folly::Optional<bool> reportProgress;
   folly::Optional<bool> treatGlobalObjectsAsRoots;
+  folly::Optional<bool> captureNumericValue;
 };
 
 struct runtime::CallFunctionOnRequest : public Request {
@@ -596,6 +604,14 @@ struct runtime::EvaluateRequest : public Request {
   folly::Optional<bool> awaitPromise;
 };
 
+struct runtime::GetHeapUsageRequest : public Request {
+  GetHeapUsageRequest();
+  explicit GetHeapUsageRequest(const folly::dynamic &obj);
+
+  folly::dynamic toDynamic() const override;
+  void accept(RequestHandler &handler) const override;
+};
+
 struct runtime::GetPropertiesRequest : public Request {
   GetPropertiesRequest();
   explicit GetPropertiesRequest(const folly::dynamic &obj);
@@ -709,6 +725,15 @@ struct runtime::EvaluateResponse : public Response {
   folly::Optional<runtime::ExceptionDetails> exceptionDetails;
 };
 
+struct runtime::GetHeapUsageResponse : public Response {
+  GetHeapUsageResponse() = default;
+  explicit GetHeapUsageResponse(const folly::dynamic &obj);
+  folly::dynamic toDynamic() const override;
+
+  double usedSize{};
+  double totalSize{};
+};
+
 struct runtime::GetPropertiesResponse : public Response {
   GetPropertiesResponse() = default;
   explicit GetPropertiesResponse(const folly::dynamic &obj);
diff --git a/ReactCommon/hermes/inspector/chrome/tests/MessageTests.cpp b/ReactCommon/hermes/inspector/chrome/tests/MessageTests.cpp
index 2b433f33aea5fe..dae6513a04b902 100644
--- a/ReactCommon/hermes/inspector/chrome/tests/MessageTests.cpp
+++ b/ReactCommon/hermes/inspector/chrome/tests/MessageTests.cpp
@@ -692,7 +692,10 @@ TEST(MessageTests, testResumeRequest) {
   std::string message = R"(
     {
       "id": 10,
-      "method": "Debugger.resume"
+      "method": "Debugger.resume",
+      "params": {
+        "terminateOnResume": false
+      }
     }
   )";
 
diff --git a/ReactCommon/hermes/inspector/tools/message_types.txt b/ReactCommon/hermes/inspector/tools/message_types.txt
index 8921a8292561cc..d2868e6ab3c331 100644
--- a/ReactCommon/hermes/inspector/tools/message_types.txt
+++ b/ReactCommon/hermes/inspector/tools/message_types.txt
@@ -32,5 +32,6 @@ Runtime.callFunctionOn
 Runtime.consoleAPICalled
 Runtime.evaluate
 Runtime.executionContextCreated
+Runtime.getHeapUsage
 Runtime.getProperties
 Runtime.runIfWaitingForDebugger
diff --git a/ReactCommon/hermes/inspector/tools/msggen/package.json b/ReactCommon/hermes/inspector/tools/msggen/package.json
index 6e42007bf68bfb..b3dcba4544fbe1 100644
--- a/ReactCommon/hermes/inspector/tools/msggen/package.json
+++ b/ReactCommon/hermes/inspector/tools/msggen/package.json
@@ -12,7 +12,7 @@
     "test": "jest"
   },
   "dependencies": {
-    "devtools-protocol": "0.0.730699",
+    "devtools-protocol": "0.0.959523",
     "yargs": "^14.2.0"
   },
   "devDependencies": {
diff --git a/ReactCommon/hermes/inspector/tools/msggen/src/ImplementationWriter.js b/ReactCommon/hermes/inspector/tools/msggen/src/ImplementationWriter.js
index 5e2b690771409b..e2ff75628271b9 100644
--- a/ReactCommon/hermes/inspector/tools/msggen/src/ImplementationWriter.js
+++ b/ReactCommon/hermes/inspector/tools/msggen/src/ImplementationWriter.js
@@ -266,13 +266,26 @@ export function emitRequestDef(stream: Writable, command: Command) {
     assign(method, obj, "method");\n\n`);
 
   if (props.length > 0) {
-    stream.write('dynamic params = obj.at("params");\n');
+    const optionalParams = props.every(p => p.optional);
+    if (optionalParams) {
+      stream.write(`
+        auto it = obj.find("params");
+        if (it != obj.items().end()) {
+          dynamic params = it->second;
+      `);
+    } else {
+      stream.write('dynamic params = obj.at("params");\n');
+    }
 
     for (const prop of props) {
       const id = prop.getCppIdentifier();
       const name = prop.name;
       stream.write(`assign(${id}, params, "${name}");\n`);
     }
+
+    if (optionalParams) {
+      stream.write('}');
+    }
   }
 
   stream.write('}\n\n');
diff --git a/ReactCommon/hermes/inspector/tools/msggen/src/index.js b/ReactCommon/hermes/inspector/tools/msggen/src/index.js
index cf6f3d881ec6ca..eb9a4f3ba96501 100644
--- a/ReactCommon/hermes/inspector/tools/msggen/src/index.js
+++ b/ReactCommon/hermes/inspector/tools/msggen/src/index.js
@@ -41,6 +41,7 @@ const proto = mergeDomains(standard, custom);
 function parseDomains(
   domainObjs: Array<any>,
   ignoreExperimental: boolean,
+  includeExperimental: Set<string>,
 ): Descriptor {
   const desc = {
     types: [],
@@ -59,7 +60,12 @@ function parseDomains(
     }
 
     for (const commandObj of obj.commands || []) {
-      const command = Command.create(domain, commandObj, ignoreExperimental);
+      const command = Command.create(
+        domain,
+        commandObj,
+        !includeExperimental.has(`${domain}.${commandObj.name}`) &&
+          ignoreExperimental,
+      );
       if (command) {
         desc.commands.push(command);
       }
@@ -199,18 +205,27 @@ function main() {
     .boolean('e')
     .alias('e', 'ignore-experimental')
     .describe('e', 'ignore experimental commands, props, and types')
+    .alias('i', 'include-experimental')
+    .describe('i', 'experimental commands to include')
     .alias('r', 'roots')
     .describe('r', 'path to a file listing root types, events, and commands')
     .nargs('r', 1)
     .demandCommand(2, 2).argv;
 
   const ignoreExperimental = !!args.e;
+  const includeExperimental = new Set(
+    typeof args.i === 'string' ? args.i.split(',') : [],
+  );
   const [headerPath, implPath] = args._;
 
   const headerStream = fs.createWriteStream(headerPath);
   const implStream = fs.createWriteStream(implPath);
 
-  const desc = parseDomains(proto.domains, ignoreExperimental);
+  const desc = parseDomains(
+    proto.domains,
+    ignoreExperimental,
+    includeExperimental,
+  );
   const graph = buildGraph(desc);
   const roots = parseRoots(desc, String(args.roots));
 
diff --git a/ReactCommon/hermes/inspector/tools/msggen/yarn.lock b/ReactCommon/hermes/inspector/tools/msggen/yarn.lock
index b6b1be6b96f535..40a02746282e98 100644
--- a/ReactCommon/hermes/inspector/tools/msggen/yarn.lock
+++ b/ReactCommon/hermes/inspector/tools/msggen/yarn.lock
@@ -2434,10 +2434,10 @@ detect-newline@^3.0.0:
   resolved "https://registry.yarnpkg.com/detect-newline/-/detect-newline-3.1.0.tgz#576f5dfc63ae1a192ff192d8ad3af6308991b651"
   integrity sha512-TLz+x/vEXm/Y7P7wn1EJFNLxYpUD4TgMosxY6fAVJUnJMbupHBOncxyWUG9OpTaH9EBD7uFI5LfEgmMOc54DsA==
 
-devtools-protocol@0.0.730699:
-  version "0.0.730699"
-  resolved "https://registry.yarnpkg.com/devtools-protocol/-/devtools-protocol-0.0.730699.tgz#4d18f6a9b7fb7cf3f1ffe73bfe14aad66cf3b2ef"
-  integrity sha512-dprBpuPzVIIXXL6GevzhvWe2wg836h3d5hY+n6IzzHbKLsUh6QlVmcIy15za0J3MhDFbmEH60s6uYsrw/tgBbw==
+devtools-protocol@0.0.959523:
+  version "0.0.959523"
+  resolved "https://registry.yarnpkg.com/devtools-protocol/-/devtools-protocol-0.0.959523.tgz#a7ce62c6b88876081fe5bec866f70e467bc021ba"
+  integrity sha512-taOcAND/oJA5FhJD2I3RA+I8RPdrpPJWwvMBPzTq7Sugev1xTOG3lgtlSfkh5xkjTYw0Ti2CRQq016goFHMoPQ==
 
 diff-sequences@^26.6.2:
   version "26.6.2"
diff --git a/ReactCommon/hermes/inspector/tools/run_msggen b/ReactCommon/hermes/inspector/tools/run_msggen
index 053cb3673727e5..c349b70be6c9e7 100755
--- a/ReactCommon/hermes/inspector/tools/run_msggen
+++ b/ReactCommon/hermes/inspector/tools/run_msggen
@@ -2,24 +2,25 @@
 
 set -e
 
-DIR=$(dirname "${BASH_SOURCE[0]}")
+DIR=$(cd -P "$(dirname "$(readlink "${BASH_SOURCE[0]}" || echo "${BASH_SOURCE[0]}")")" && pwd)
 cd "${DIR}/msggen"
 
 yarn install
 yarn build
 
-FBSOURCE=$(hg root)
-MSGTYPES_PATH="${FBSOURCE}/xplat/js/react-native-github/ReactCommon/hermes/inspector/tools/message_types.txt"
-HEADER_PATH="${FBSOURCE}/xplat/js/react-native-github/ReactCommon/hermes/inspector/chrome/MessageTypes.h"
-CPP_PATH="${FBSOURCE}/xplat/js/react-native-github/ReactCommon/hermes/inspector/chrome/MessageTypes.cpp"
+MSGTYPES_PATH="${DIR}/message_types.txt"
+HEADER_PATH="${DIR}/../chrome/MessageTypes.h"
+CPP_PATH="${DIR}/../chrome/MessageTypes.cpp"
 
 node bin/index.js \
   --ignore-experimental \
+  --include-experimental=Runtime.getHeapUsage \
   --roots "$MSGTYPES_PATH" \
   "$HEADER_PATH" "$CPP_PATH"
 
 clang-format -i --style=file "$HEADER_PATH"
 clang-format -i --style=file "$CPP_PATH"
 
+FBSOURCE=$(hg root)
 "${FBSOURCE}/tools/signedsource" sign "$HEADER_PATH"
 "${FBSOURCE}/tools/signedsource" sign "$CPP_PATH"