diff --git a/API/hermes/TracingRuntime.h b/API/hermes/TracingRuntime.h
index 59c72b17089..c7c455889a8 100644
--- a/API/hermes/TracingRuntime.h
+++ b/API/hermes/TracingRuntime.h
@@ -140,6 +140,13 @@ class TracingRuntime : public jsi::RuntimeDecorator<jsi::Runtime>
   jsi::Value getPrototypeOf(const jsi::Object &object) override;
 
   jsi::Array getPropertyNames(const jsi::Object &o) override;
+  // Uses the default implementation of jsi::Runtime, which calls the traced
+  // getPropertyNames and the other traced methods, so replay sees the same
+  // calls.
+  std::vector<jsi::PropNameID> getPropertyNameIDs(
+      const jsi::Object &o) override {
+    return jsi::Runtime::getPropertyNameIDs(o);
+  }
 
   jsi::WeakObject createWeakObject(const jsi::Object &o) override;
 
diff --git a/API/hermes/hermes.cpp b/API/hermes/hermes.cpp
index 0f96516c5f2..370de573d4d 100644
--- a/API/hermes/hermes.cpp
+++ b/API/hermes/hermes.cpp
@@ -882,6 +882,8 @@ class HermesRuntimeImpl final : public HermesRuntime,
   bool isHostObject(const jsi::Object &) const override;
   bool isHostFunction(const jsi::Function &) const override;
   jsi::Array getPropertyNames(const jsi::Object &) override;
+  std::vector<jsi::PropNameID> getPropertyNameIDs(
+      const jsi::Object &obj) override;
 
   void setPrototypeOf(const jsi::Object &object, const jsi::Value &prototype)
       override;
@@ -3118,6 +3120,49 @@ jsi::Array HermesRuntimeImpl::getPropertyNames(const jsi::Object &obj) {
   return ret;
 }
 
+std::vector<jsi::PropNameID> HermesRuntimeImpl::getPropertyNameIDs(
+    const jsi::Object &obj) {
+  ExecutionScopeRAII scopeRAII(mutatorScope);
+  vm::GCScope gcScope(runtime_);
+  uint32_t beginIndex;
+  uint32_t endIndex;
+  vm::CallResult<vm::Handle<vm::ArrayStorageSmall>> cr =
+      vm::getForInPropertyNames(runtime_, handle(obj), beginIndex, endIndex);
+  checkStatus(cr.getStatus());
+  vm::Handle<vm::ArrayStorageSmall> names = *cr;
+
+  std::vector<jsi::PropNameID> result;
+  result.reserve(endIndex - beginIndex);
+  for (uint32_t i = beginIndex; i < endIndex; ++i) {
+    vm::GCScopeMarkerRAII marker{runtime_};
+    vm::SmallHermesValue name = names->at(i);
+    if (name.isSymbol()) {
+      // for-in keeps the names of ordinary objects as symbols, which are what
+      // a PropNameID holds.
+      result.push_back(add<jsi::PropNameID>(
+          vm::HermesValue::encodeSymbolValue(name.getSymbol())));
+      continue;
+    }
+    vm::StringPrimitive *str;
+    if (name.isString()) {
+      str = name.getString(runtime_);
+    } else if (name.isNumber()) {
+      // May allocate. 'name' must not be used afterwards.
+      auto strRes =
+          vm::numberToStringPrimitive(runtime_, name.getNumber(runtime_));
+      checkStatus(strRes.getStatus());
+      str = strRes->get();
+    } else {
+      llvm_unreachable("property name is not String, Symbol or Number");
+    }
+    auto symbolRes =
+        vm::stringToSymbolID(runtime_, vm::createPseudoHandle(str));
+    checkStatus(symbolRes.getStatus());
+    result.push_back(add<jsi::PropNameID>(symbolRes->getHermesValue()));
+  }
+  return result;
+}
+
 jsi::WeakObject HermesRuntimeImpl::createWeakObject(const jsi::Object &obj) {
   ExecutionScopeRAII scopeRAII(mutatorScope);
   return addWeak(
diff --git a/API/jsi/jsi/decorator.h b/API/jsi/jsi/decorator.h
index f91720b4194..5ee17d5153e 100644
--- a/API/jsi/jsi/decorator.h
+++ b/API/jsi/jsi/decorator.h
@@ -403,6 +403,9 @@ class RuntimeDecorator : public Base, private jsi::Instrumentation {
   Array getPropertyNames(const Object& o) override {
     return plain_.getPropertyNames(o);
   }
+  std::vector<PropNameID> getPropertyNameIDs(const Object& o) override {
+    return plain_.getPropertyNameIDs(o);
+  }
 
   WeakObject createWeakObject(const Object& o) override {
     return plain_.createWeakObject(o);
@@ -1043,6 +1046,10 @@ class WithRuntimeDecorator : public RuntimeDecorator<Plain, Base> {
     Around around{with_};
     return RD::getPropertyNames(o);
   }
+  std::vector<PropNameID> getPropertyNameIDs(const Object& o) override {
+    Around around{with_};
+    return RD::getPropertyNameIDs(o);
+  }
 
   WeakObject createWeakObject(const Object& o) override {
     Around around{with_};
diff --git a/API/jsi/jsi/jsi-inl.h b/API/jsi/jsi/jsi-inl.h
index 6a29f64798b..b5323b9ff54 100644
--- a/API/jsi/jsi/jsi-inl.h
+++ b/API/jsi/jsi/jsi-inl.h
@@ -297,6 +297,11 @@ inline Array Object::getPropertyNames(IRuntime& runtime) const {
   return runtime.getPropertyNames(*this);
 }
 
+inline std::vector<PropNameID> Object::getPropertyNameIDs(
+    IRuntime& runtime) const {
+  return runtime.getPropertyNameIDs(*this);
+}
+
 inline Value WeakObject::lock(IRuntime& runtime) const {
   return runtime.lockWeakObject(*this);
 }
diff --git a/API/jsi/jsi/jsi.cpp b/API/jsi/jsi/jsi.cpp
index 521001a8980..726ae8cf370 100644
--- a/API/jsi/jsi/jsi.cpp
+++ b/API/jsi/jsi/jsi.cpp
@@ -459,6 +459,18 @@ void Runtime::deleteProperty(const Object& object, const Value& name) {
   }
 }
 
+std::vector<PropNameID> Runtime::getPropertyNameIDs(const Object& object) {
+  Array names = getPropertyNames(object);
+  size_t count = names.size(*this);
+  std::vector<PropNameID> result;
+  result.reserve(count);
+  for (size_t i = 0; i < count; ++i) {
+    result.push_back(PropNameID::forString(
+        *this, names.getValueAtIndex(*this, i).getString(*this)));
+  }
+  return result;
+}
+
 size_t Runtime::push(const Array& arr, const Value* elements, size_t count) {
   size_t newSize = size(arr);
   for (size_t i = 0; i < count; i++) {
diff --git a/API/jsi/jsi/jsi.h b/API/jsi/jsi/jsi.h
index bf98028fb3f..2ab45328374 100644
--- a/API/jsi/jsi/jsi.h
+++ b/API/jsi/jsi/jsi.h
@@ -558,6 +558,9 @@ class JSI_EXPORT IRuntime : public ICast {
   virtual bool isHostObject(const jsi::Object&) const = 0;
   virtual bool isHostFunction(const jsi::Function&) const = 0;
   virtual Array getPropertyNames(const Object&) = 0;
+  /// Returns the same names as getPropertyNames, in the same order, as
+  /// PropNameIDs and without creating a JS array.
+  virtual std::vector<PropNameID> getPropertyNameIDs(const Object& object) = 0;
 
   virtual WeakObject createWeakObject(const Object&) = 0;
   virtual Value lockWeakObject(const WeakObject&) = 0;
@@ -731,6 +734,7 @@ class JSI_EXPORT Runtime : public IRuntime {
   void deleteProperty(const Object&, const PropNameID& name) override;
   void deleteProperty(const Object&, const String& name) override;
   void deleteProperty(const Object&, const Value& name) override;
+  std::vector<PropNameID> getPropertyNameIDs(const Object& object) override;
 
   void setRuntimeDataImpl(
       const UUID& uuid,
@@ -1419,6 +1423,11 @@ class JSI_EXPORT Object : public Pointer {
   /// works.  I only need it in one place.)
   Array getPropertyNames(IRuntime& runtime) const;
 
+  /// \return the names of all enumerable properties in the object and its
+  /// prototype chain, as getPropertyNames does, but as PropNameIDs, which can
+  /// be used to get the property values without converting the names again.
+  std::vector<PropNameID> getPropertyNameIDs(IRuntime& runtime) const;
+
   /// Inform the runtime that there is additional memory associated with a given
   /// JavaScript object that is not visible to the GC. This can be used if an
   /// object is known to retain some native memory, and may be used to guide
diff --git a/API/jsi/jsi/test/testlib.cpp b/API/jsi/jsi/test/testlib.cpp
index 37b71538b87..53d215b4f8f 100644
--- a/API/jsi/jsi/test/testlib.cpp
+++ b/API/jsi/jsi/test/testlib.cpp
@@ -2222,6 +2222,47 @@ TEST_P(JSITest, GetStringDataTest) {
   EXPECT_EQ(buf, str.utf16(rd));
 }
 
+TEST_P(JSITest, GetPropertyNameIDsTest) {
+  // This Runtime Decorator is used to test the default getPropertyNameIDs
+  // implementation for VMs that do not provide their own implementation
+  class RD : public RuntimeDecorator<Runtime, Runtime> {
+   public:
+    explicit RD(Runtime& rt) : RuntimeDecorator(rt) {}
+
+    std::vector<PropNameID> getPropertyNameIDs(const Object& object) override {
+      return Runtime::getPropertyNameIDs(object);
+    }
+  };
+  RD rd(rt);
+
+  for (const char* source :
+       {"({title: 1, 7: 2, '\\u00e9t\\u00e9': 3, [Symbol('s')]: 4, x: null})",
+        "[10, 20, 30]",
+        "(function() {"
+        "  var o = Object.create({inherited: 1});"
+        "  o.own = 2;"
+        "  Object.defineProperty(o, 'getter', {"
+        "    get: function() { return 3; }, enumerable: true});"
+        "  Object.defineProperty(o, 'hidden', {value: 4, enumerable: false});"
+        "  return o;"
+        "})()",
+        "({})"}) {
+    Object obj = eval(source).getObject(rt);
+    Array names = obj.getPropertyNames(rt);
+    for (Runtime* runtime : {static_cast<Runtime*>(&rt), static_cast<Runtime*>(&rd)}) {
+      std::vector<PropNameID> ids = obj.getPropertyNameIDs(*runtime);
+      ASSERT_EQ(ids.size(), names.size(rt)) << source;
+      for (size_t i = 0; i < ids.size(); ++i) {
+        String name = names.getValueAtIndex(rt, i).getString(rt);
+        EXPECT_EQ(ids[i].utf8(rt), name.utf8(rt)) << source;
+        EXPECT_TRUE(Value::strictEquals(
+            rt, obj.getProperty(rt, ids[i]), obj.getProperty(rt, name)))
+            << source;
+      }
+    }
+  }
+}
+
 TEST_P(JSITest, ObjectSetPrototype) {
   // This Runtime Decorator is used to test the default implementation of
   // Object.setPrototypeOf