diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index e1823bd5..4b5a4bfc 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -560,7 +560,7 @@ inline PyThreadState *get_thread_state_unchecked() {
 
 // Forward declarations
 inline void keep_alive_impl(handle nurse, handle patient);
-inline PyObject *make_new_instance(PyTypeObject *type, bool allocate_value = true);
+inline PyObject *make_new_instance(PyTypeObject *type);
 
 class type_caster_generic {
 public:
@@ -591,7 +591,7 @@ public:
             }
         }
 
-        auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type, false /* don't allocate value */));
+        auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type));
         auto wrapper = reinterpret_cast<instance *>(inst.ptr());
         wrapper->owned = false;
         void *&valueptr = values_and_holders(wrapper).begin()->value_ptr();
@@ -647,8 +647,14 @@ public:
 protected:
 
     // Base methods for generic caster; there are overridden in copyable_holder_caster
-    void load_value(const value_and_holder &v_h) {
-        value = v_h.value_ptr();
+    void load_value(value_and_holder &&v_h) {
+        auto *&vptr = v_h.value_ptr();
+        // Lazy allocation for unallocated values:
+        if (vptr == nullptr) {
+            auto *type = v_h.type ? v_h.type : typeinfo;
+            vptr = type->operator_new(type->type_size);
+        }
+        value = vptr;
     }
     bool try_implicit_casts(handle src, bool convert) {
         for (auto &cast : typeinfo->implicit_casts) {
diff --git a/include/pybind11/detail/class.h b/include/pybind11/detail/class.h
index 6f9667e0..40efabcc 100644
--- a/include/pybind11/detail/class.h
+++ b/include/pybind11/detail/class.h
@@ -232,11 +232,10 @@ inline bool deregister_instance(instance *self, void *valptr, const type_info *t
     return ret;
 }
 
-/// Instance creation function for all pybind11 types. It only allocates space for the C++ object
-/// (or multiple objects, for Python-side inheritance from multiple pybind11 types), but doesn't
-/// call the constructor -- an `__init__` function must do that (followed by an `init_instance`
-/// to set up the holder and register the instance).
-inline PyObject *make_new_instance(PyTypeObject *type, bool allocate_value /*= true (in cast.h)*/) {
+/// Instance creation function for all pybind11 types. It allocates the internal instance layout for
+/// holding C++ objects and holders.  Allocation is done lazily (the first time the instance is cast
+/// to a reference or pointer), and initialization is done by an `__init__` function.
+inline PyObject *make_new_instance(PyTypeObject *type) {
 #if defined(PYPY_VERSION)
     // PyPy gets tp_basicsize wrong (issue 2482) under multiple inheritance when the first inherited
     // object is a a plain Python type (i.e. not derived from an extension type).  Fix it.
@@ -251,13 +250,6 @@ inline PyObject *make_new_instance(PyTypeObject *type, bool allocate_value /*= t
     inst->allocate_layout();
 
     inst->owned = true;
-    // Allocate (if requested) the value pointers; otherwise leave them as nullptr
-    if (allocate_value) {
-        for (auto &v_h : values_and_holders(inst)) {
-            void *&vptr = v_h.value_ptr();
-            vptr = v_h.type->operator_new(v_h.type->type_size);
-        }
-    }
 
     return self;
 }
diff --git a/include/pybind11/detail/common.h b/include/pybind11/detail/common.h
index 2201d2b2..c7b69f58 100644
--- a/include/pybind11/detail/common.h
+++ b/include/pybind11/detail/common.h
@@ -434,7 +434,7 @@ struct instance {
     /// If true, get_internals().patients has an entry for this object
     bool has_patients : 1;
 
-    /// Initializes all of the above type/values/holders data
+    /// Initializes all of the above type/values/holders data (but not the instance values themselves)
     void allocate_layout();
 
     /// Destroys/deallocates all of the above