diff --git a/src/cgutils.cpp b/src/cgutils.cpp
index 8ce84acb30901..c73b83a38d0ff 100644
--- a/src/cgutils.cpp
+++ b/src/cgutils.cpp
@@ -43,6 +43,22 @@ STATISTIC(EmittedWriteBarriers, "Number of write barriers emitted");
 STATISTIC(EmittedNewStructs, "Number of new structs emitted");
 STATISTIC(EmittedDeferSignal, "Number of deferred signals emitted");
 
+#ifdef JL_DISPATCH_LOG_BOXES
+static Value *emit_sizeof(jl_codectx_t &ctx, const jl_cgval_t &p);
+void logbox(jl_codectx_t &ctx, const jl_cgval_t &vinfo, jl_count_box_type log_reason)
+{
+    if (log_reason != JL_DONT_LOG_BOX) {
+        Function *F;
+        if (log_reason == JL_COUNT_BOX_INPUTS) {
+            F = prepare_call(jllogboxinput_func);
+        } else {
+            F = prepare_call(jllogboxreturn_func);
+        }
+        ctx.builder.CreateCall(F, emit_sizeof(ctx, vinfo));
+    }
+}
+#endif
+
 static Value *track_pjlvalue(jl_codectx_t &ctx, Value *V)
 {
     assert(V->getType() == ctx.types().T_pjlvalue);
@@ -999,8 +1015,11 @@ static LoadInst *emit_nthptr_recast(jl_codectx_t &ctx, Value *v, Value *idx, MDN
     return load;
 }
 
+#ifdef JL_DISPATCH_LOG_BOXES
+static Value *boxed(jl_codectx_t &ctx, const jl_cgval_t &v,  bool is_promotable=false, jl_count_box_type log_reason=JL_DONT_LOG_BOX);
+#else
 static Value *boxed(jl_codectx_t &ctx, const jl_cgval_t &v,  bool is_promotable=false);
-
+#endif
 static Value *emit_typeof(jl_codectx_t &ctx, Value *v, bool maybenull);
 
 static jl_cgval_t emit_typeof(jl_codectx_t &ctx, const jl_cgval_t &p, bool maybenull)
@@ -1107,7 +1126,6 @@ static Value *emit_datatype_size(jl_codectx_t &ctx, Value *dt)
     return ai.decorateInst(ctx.builder.CreateAlignedLoad(getInt32Ty(ctx.builder.getContext()), Ptr, Align(sizeof(int32_t))));
 }
 
-/* this is valid code, it's simply unused
 static Value *emit_sizeof(jl_codectx_t &ctx, const jl_cgval_t &p)
 {
     if (p.TIndex) {
@@ -1130,7 +1148,7 @@ static Value *emit_sizeof(jl_codectx_t &ctx, const jl_cgval_t &p)
                     ConstantInt::get(getInt8Ty(ctx.builder.getContext()), 0));
             ctx.builder.CreateCondBr(isboxed, dynloadBB, postBB);
             ctx.builder.SetInsertPoint(dynloadBB);
-            Value *datatype = emit_typeof(p.V);
+            Value *datatype = emit_typeof(ctx, p.V, false);
             Value *dyn_size = emit_datatype_size(ctx, datatype);
             ctx.builder.CreateBr(postBB);
             dynloadBB = ctx.builder.GetInsertBlock(); // could have changed
@@ -1156,6 +1174,7 @@ static Value *emit_sizeof(jl_codectx_t &ctx, const jl_cgval_t &p)
     }
 }
 
+/* this is valid code, it's simply unused
 static Value *emit_datatype_mutabl(jl_codectx_t &ctx, Value *dt)
 {
     jl_aliasinfo_t ai = jl_aliasinfo_t::fromTBAA(ctx, ctx.tbaa().tbaa_const);
@@ -3029,9 +3048,18 @@ static Value *load_i8box(jl_codectx_t &ctx, Value *v, jl_datatype_t *ty)
             (jl_value_t*)ty));
 }
 
+#ifdef JL_DISPATCH_LOG_BOXES
+static Value *_boxed_special(jl_codectx_t &ctx, const jl_cgval_t &vinfo, Type *t, jl_count_box_type log_reason=JL_DONT_LOG_BOX);
+#else
+static Value *_boxed_special(jl_codectx_t &ctx, const jl_cgval_t &vinfo, Type *t);
+#endif
 // some types have special boxing functions with small-value caches
 // Returns ctx.types().T_prjlvalue
+#ifdef JL_DISPATCH_LOG_BOXES
+static Value *_boxed_special(jl_codectx_t &ctx, const jl_cgval_t &vinfo, Type *t, jl_count_box_type log_reason)
+#else
 static Value *_boxed_special(jl_codectx_t &ctx, const jl_cgval_t &vinfo, Type *t)
+#endif
 {
     jl_value_t *jt = vinfo.typ;
     if (jt == (jl_value_t*)jl_bool_type)
@@ -3087,6 +3115,11 @@ static Value *_boxed_special(jl_codectx_t &ctx, const jl_cgval_t &vinfo, Type *t
         assert(jb->instance != NULL);
         return track_pjlvalue(ctx, literal_pointer_val(ctx, jb->instance));
     }
+#ifdef JL_DISPATCH_LOG_BOXES
+    if (log_reason != JL_DONT_LOG_BOX && box && jb != jl_int8_type) {
+        logbox(ctx, vinfo, log_reason);
+    }
+#endif
     return box;
 }
 
@@ -3160,6 +3193,11 @@ static AllocaInst *try_emit_union_alloca(jl_codectx_t &ctx, jl_uniontype_t *ut,
     return NULL;
 }
 
+#ifdef JL_DISPATCH_LOG_BOXES
+static Value *box_union(jl_codectx_t &ctx, const jl_cgval_t &vinfo, const SmallBitVector &skip, jl_count_box_type log_reason=JL_DONT_LOG_BOX);
+#else
+static Value *box_union(jl_codectx_t &ctx, const jl_cgval_t &vinfo, const SmallBitVector &skip);
+#endif
 /*
  * Box unboxed values in a union. Optionally, skip certain unboxed values,
  * returning `Constant::getNullValue(ctx.types().T_pjlvalue)` in one of the skipped cases. If `skip` is not empty,
@@ -3168,7 +3206,11 @@ static AllocaInst *try_emit_union_alloca(jl_codectx_t &ctx, jl_uniontype_t *ut,
  * `vinfo` is already an unknown boxed union (union tag 0x80).
  */
 // Returns ctx.types().T_prjlvalue
+#ifdef JL_DISPATCH_LOG_BOXES
+static Value *box_union(jl_codectx_t &ctx, const jl_cgval_t &vinfo, const SmallBitVector &skip, jl_count_box_type log_reason)
+#else
 static Value *box_union(jl_codectx_t &ctx, const jl_cgval_t &vinfo, const SmallBitVector &skip)
+#endif
 {
     // given vinfo::Union{T, S}, emit IR of the form:
     //   ...
@@ -3206,10 +3248,19 @@ static Value *box_union(jl_codectx_t &ctx, const jl_cgval_t &vinfo, const SmallB
                 }
                 else {
                     jl_cgval_t vinfo_r = jl_cgval_t(vinfo, (jl_value_t*)jt, NULL);
+#ifdef JL_DISPATCH_LOG_BOXES
+                    box = _boxed_special(ctx, vinfo_r, t, log_reason);
+#else
                     box = _boxed_special(ctx, vinfo_r, t);
+#endif
                     if (!box) {
                         box = emit_allocobj(ctx, jl_datatype_size(jt), literal_pointer_val(ctx, (jl_value_t*)jt));
                         init_bits_cgval(ctx, box, vinfo_r, jl_is_mutable(jt) ? ctx.tbaa().tbaa_mutab : ctx.tbaa().tbaa_immut);
+#ifdef JL_DISPATCH_LOG_BOXES
+                        if (log_reason != JL_DONT_LOG_BOX) {
+                            logbox(ctx, vinfo_r, log_reason);
+                        }
+#endif
                     }
                 }
                 tempBB = ctx.builder.GetInsertBlock(); // could have changed
@@ -3303,7 +3354,11 @@ static void recursively_adjust_ptr_type(llvm::Value *Val, unsigned FromAS, unsig
 // dynamically-typed value is required (e.g. argument to unknown function).
 // if it's already a pointer it's left alone.
 // Returns ctx.types().T_prjlvalue
+#ifdef JL_DISPATCH_LOG_BOXES
+static Value *boxed(jl_codectx_t &ctx, const jl_cgval_t &vinfo, bool is_promotable, jl_count_box_type log_reason)
+#else
 static Value *boxed(jl_codectx_t &ctx, const jl_cgval_t &vinfo, bool is_promotable)
+#endif
 {
     jl_value_t *jt = vinfo.typ;
     if (jt == jl_bottom_type || jt == NULL)
@@ -3323,14 +3378,22 @@ static Value *boxed(jl_codectx_t &ctx, const jl_cgval_t &vinfo, bool is_promotab
     Value *box;
     if (vinfo.TIndex) {
         SmallBitVector skip_none;
+#ifdef JL_DISPATCH_LOG_BOXES
+        box = box_union(ctx, vinfo, skip_none, log_reason);
+#else
         box = box_union(ctx, vinfo, skip_none);
+#endif
     }
     else {
         assert(vinfo.V && "Missing data for unboxed value.");
         assert(jl_is_concrete_immutable(jt) && "This type shouldn't have been unboxed.");
         Type *t = julia_type_to_llvm(ctx, jt);
         assert(!type_is_ghost(t)); // ghost values should have been handled by vinfo.constant above!
+#ifdef JL_DISPATCH_LOG_BOXES
+        box = _boxed_special(ctx, vinfo, t, log_reason);
+#else
         box = _boxed_special(ctx, vinfo, t);
+#endif
         if (!box) {
             bool do_promote = vinfo.promotion_point;
             if (do_promote && is_promotable) {
@@ -3353,6 +3416,11 @@ static Value *boxed(jl_codectx_t &ctx, const jl_cgval_t &vinfo, bool is_promotab
                 box = emit_allocobj(ctx, jl_datatype_size(jt), literal_pointer_val(ctx, (jl_value_t*)jt));
                 init_bits_cgval(ctx, box, vinfo, jl_is_mutable(jt) ? ctx.tbaa().tbaa_mutab : ctx.tbaa().tbaa_immut);
             }
+#ifdef JL_DISPATCH_LOG_BOXES
+            if (log_reason != JL_DONT_LOG_BOX) {
+                logbox(ctx, vinfo, log_reason);
+            }
+#endif
         }
     }
     return box;
diff --git a/src/codegen.cpp b/src/codegen.cpp
index a4773acb3fbea..53bcded3583c5 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -889,6 +889,22 @@ static const auto jlegalx_func = new JuliaFunction{
             AttributeSet(),
             None); },
 };
+#ifdef JL_DISPATCH_LOG_BOXES
+static const auto jllogboxinput_func = new JuliaFunction{
+    XSTR(jl_log_box_input),
+    [](LLVMContext &C) {
+        return FunctionType::get(getVoidTy(C), {getInt32Ty(C)}, false);
+    },
+    nullptr,
+};
+static const auto jllogboxreturn_func = new JuliaFunction{
+    XSTR(jl_log_box_return),
+    [](LLVMContext &C) {
+        return FunctionType::get(getVoidTy(C), {getInt32Ty(C)}, false);
+    },
+    nullptr,
+};
+#endif
 static const auto jl_alloc_obj_func = new JuliaFunction{
     "julia.gc_alloc_obj",
     [](LLVMContext &C) {
@@ -4072,7 +4088,12 @@ static CallInst *emit_jlcall(jl_codectx_t &ctx, FunctionCallee theFptr, Value *t
     if (theF)
         theArgs.push_back(theF);
     for (size_t i = 0; i < nargs; i++) {
+#ifdef JL_DISPATCH_LOG_BOXES
+        // log the boxed arguments for this call
+        Value *arg = boxed(ctx, argv[i], false, JL_COUNT_BOX_INPUTS);
+#else
         Value *arg = boxed(ctx, argv[i]);
+#endif
         theArgs.push_back(arg);
     }
     CallInst *result = ctx.builder.CreateCall(TheTrampoline, theArgs);
@@ -6723,7 +6744,12 @@ static Function *gen_invoke_wrapper(jl_method_instance_t *lam, jl_value_t *jlret
             break;
         }
     }
+#ifdef JL_DISPATCH_LOG_BOXES
+    // log the box for this return value
+    ctx.builder.CreateRet(boxed(ctx, retval, false, JL_COUNT_BOX_RETURNS));
+#else
     ctx.builder.CreateRet(boxed(ctx, retval));
+#endif
     return w;
 }
 
@@ -8224,7 +8250,12 @@ static jl_llvm_functions_t
                     else if (VN->getType() == ctx.types().T_prjlvalue) {
                         // Includes the jl_is_uniontype(phiType) && !TindexN case
                         // TODO: if convert_julia_type says it is wasted effort and to skip it, is it worth using Constant::getNullValue(ctx.types().T_prjlvalue) (dynamically)?
+#ifdef JL_DISPATCH_LOG_BOXES
+                        // NOTE(PR): This one is the boxing for hash.
+                        V = boxed(ctx, val, false, JL_COUNT_BOX_INPUTS);
+#else
                         V = boxed(ctx, val);
+#endif
                     }
                     else {
                         // must be careful to emit undef here (rather than a bitcast or
diff --git a/src/gc-alloc-profiler.cpp b/src/gc-alloc-profiler.cpp
index 1bcbeb2189f5f..f0c0dde410066 100644
--- a/src/gc-alloc-profiler.cpp
+++ b/src/gc-alloc-profiler.cpp
@@ -78,6 +78,90 @@ jl_raw_backtrace_t get_raw_backtrace() JL_NOTSAFEPOINT {
 
 extern "C" {  // Needed since these functions doesn't take any arguments.
 
+uint64_t num_boxed_inputs;
+uint64_t boxed_inputs_size;
+uint64_t extra_num_boxed_inputs;
+uint64_t extra_boxed_inputs_size;
+uint64_t num_boxed_returns;
+uint64_t boxed_returns_size;
+
+JL_DLLEXPORT uint64_t jl_total_boxes()
+{
+    return num_boxed_inputs + extra_num_boxed_inputs + num_boxed_returns;
+}
+JL_DLLEXPORT uint64_t jl_total_boxes_size()
+{
+    return boxed_inputs_size + extra_boxed_inputs_size + boxed_returns_size;
+}
+JL_DLLEXPORT uint64_t jl_num_boxed_inputs()
+{
+    return num_boxed_inputs;
+}
+JL_DLLEXPORT uint64_t jl_boxed_inputs_size()
+{
+    return boxed_inputs_size;
+}
+JL_DLLEXPORT uint64_t jl_extra_num_boxed_inputs()
+{
+    return extra_num_boxed_inputs;
+}
+JL_DLLEXPORT uint64_t jl_extra_boxed_inputs_size()
+{
+    return extra_boxed_inputs_size;
+}
+JL_DLLEXPORT uint64_t jl_num_boxed_returns()
+{
+    return num_boxed_returns;
+}
+JL_DLLEXPORT uint64_t jl_boxed_returns_size()
+{
+    return boxed_returns_size;
+}
+
+static float extra_allocs_rate = 0.0f;
+JL_DLLEXPORT void jl_set_extra_allocs_rate(float rate)
+{
+    extra_allocs_rate = rate;
+}
+
+#ifdef JL_DISPATCH_LOG_BOXES
+JL_DLLEXPORT void jl_log_box_input(int32_t sz)
+{
+    num_boxed_inputs++;
+    boxed_inputs_size += sz;
+
+    // Randomly, with a probability of `extra_allocs_rate`, record some number of
+    // extra allocations. The goal is to estimate the impact of _reducing_ the
+    // number of allocations for boxing. For a rate >1, more than one allocation
+    // may be recorded: we pick a random number between 0 and extra_allocs_rate,
+    // then round it and allocate that many extra objects.
+    if (extra_allocs_rate > 0.0f) {
+        float num_extra_allocs = extra_allocs_rate;
+        jl_value_t *extra_obj;
+        while (num_extra_allocs > 1) {
+            num_extra_allocs--;
+            extra_num_boxed_inputs++;
+            extra_boxed_inputs_size += sz;
+            extra_obj = jl_gc_allocobj(sz);
+            memset(extra_obj, 0, sz);
+        }
+        // decide whether or not to allocate for the last one
+        float sample = float(rand()) / float(RAND_MAX);
+        if (sample < num_extra_allocs) {
+            extra_num_boxed_inputs++;
+            extra_boxed_inputs_size += sz;
+            extra_obj = jl_gc_allocobj(sz);
+            memset(extra_obj, 0, sz);
+        }
+    }
+}
+JL_DLLEXPORT void jl_log_box_return(int32_t sz)
+{
+    num_boxed_returns++;
+    boxed_returns_size += sz;
+}
+#endif
+
 JL_DLLEXPORT void jl_start_alloc_profile(double sample_rate) {
     // We only need to do this once, the first time this is called.
     size_t nthreads = jl_atomic_load_acquire(&jl_n_threads);
diff --git a/src/gc-alloc-profiler.h b/src/gc-alloc-profiler.h
index fcd8e45caa2d8..e6c147913fa1d 100644
--- a/src/gc-alloc-profiler.h
+++ b/src/gc-alloc-profiler.h
@@ -17,6 +17,14 @@ extern "C" {
 // Forward-declaration to avoid dependency in header file.
 struct jl_raw_alloc_t;  // Defined in gc-alloc-profiler.cpp
 
+#ifdef JL_DISPATCH_LOG_BOXES
+enum jl_count_box_type {
+    JL_DONT_LOG_BOX,
+    JL_COUNT_BOX_INPUTS,
+    JL_COUNT_BOX_RETURNS,
+};
+#endif
+
 typedef struct {
     struct jl_raw_alloc_t *allocs;
     size_t num_allocs;
diff --git a/src/gf.c b/src/gf.c
index 33849dd5aa387..9a5a720f3afbc 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -2933,13 +2933,46 @@ STATIC_INLINE jl_method_instance_t *jl_lookup_generic_(jl_value_t *F, jl_value_t
 JL_DLLEXPORT jl_value_t *jl_apply_generic(jl_value_t *F, jl_value_t **args, uint32_t nargs)
 {
     size_t world = jl_current_task->world_age;
+#ifdef JL_DISPATCH_LOG_BOXES
+    uint64_t t0 = jl_hrtime();
+#endif
     jl_method_instance_t *mfunc = jl_lookup_generic_(F, args, nargs,
                                                      jl_int32hash_fast(jl_return_address()),
                                                      world);
     JL_GC_PROMISE_ROOTED(mfunc);
+
+#ifdef JL_DISPATCH_LOG_BOXES
+    jl_method_t *def = mfunc->def.method;
+    if (jl_is_method(def)) {
+        def->num_dynamic_dispatches++;
+        def->dynamic_dispatch_ns += (jl_hrtime() - t0);
+    }
+#endif
     return _jl_invoke(F, args, nargs, mfunc, world);
 }
 
+#ifdef JL_DISPATCH_LOG_BOXES
+JL_DLLEXPORT int32_t jl_get_num_dynamic_dispatches(jl_method_t *m)
+{
+    return (m && jl_is_method(m)) ? m->num_dynamic_dispatches : 0;
+}
+JL_DLLEXPORT int64_t jl_get_dynamic_dispatch_ns(jl_method_t *m)
+{
+    return (m && jl_is_method(m)) ? m->dynamic_dispatch_ns : 0;
+}
+#else
+JL_DLLEXPORT int32_t jl_get_num_dynamic_dispatches(jl_method_t *m)
+{
+    jl_error("not logging");
+    return 0;
+}
+JL_DLLEXPORT int64_t jl_get_dynamic_dispatch_ns(jl_method_t *m)
+{
+    jl_error("not logging");
+    return 0;
+}
+#endif
+
 static jl_method_match_t *_gf_invoke_lookup(jl_value_t *types JL_PROPAGATES_ROOT, jl_value_t *mt, size_t world, size_t *min_valid, size_t *max_valid)
 {
     jl_value_t *unw = jl_unwrap_unionall((jl_value_t*)types);
diff --git a/src/jltypes.c b/src/jltypes.c
index 0767e9493bbc0..fc651befca365 100644
--- a/src/jltypes.c
+++ b/src/jltypes.c
@@ -2600,7 +2600,7 @@ void jl_init_types(void) JL_GC_DISABLED
     jl_method_type =
         jl_new_datatype(jl_symbol("Method"), core,
                         jl_any_type, jl_emptysvec,
-                        jl_perm_symsvec(29,
+                        jl_perm_symsvec(31,
                             "name",
                             "module",
                             "file",
@@ -2629,8 +2629,10 @@ void jl_init_types(void) JL_GC_DISABLED
                             "pure",
                             "is_for_opaque_closure",
                             "constprop",
-                            "purity"),
-                        jl_svec(29,
+                            "purity",
+                            "num_dynamic_dispatches",
+                            "dynamic_dispatch_ns"),
+                        jl_svec(31,
                             jl_symbol_type,
                             jl_module_type,
                             jl_symbol_type,
@@ -2659,7 +2661,9 @@ void jl_init_types(void) JL_GC_DISABLED
                             jl_bool_type,
                             jl_bool_type,
                             jl_uint8_type,
-                            jl_uint8_type),
+                            jl_uint8_type,
+                            jl_int32_type,
+                            jl_int64_type),
                         jl_emptysvec,
                         0, 1, 10);
     //const static uint32_t method_constfields[1] = { 0x03fc065f }; // (1<<0)|(1<<1)|(1<<2)|(1<<3)|(1<<4)|(1<<6)|(1<<9)|(1<<10)|(1<<18)|(1<<19)|(1<<20)|(1<<21)|(1<<22)|(1<<23)|(1<<24)|(1<<25);
diff --git a/src/julia.h b/src/julia.h
index a34c1f06d0cc1..2da6c78941616 100644
--- a/src/julia.h
+++ b/src/julia.h
@@ -348,6 +348,9 @@ typedef struct _jl_method_t {
     // forcing the conclusion to always true.
     _jl_purity_overrides_t purity;
 
+    int32_t num_dynamic_dispatches;
+    int64_t dynamic_dispatch_ns;
+
 // hidden fields:
     // lock for modifications to the method
     jl_mutex_t writelock;
diff --git a/src/method.c b/src/method.c
index 4e48ef9122d79..e70b0a159f179 100644
--- a/src/method.c
+++ b/src/method.c
@@ -805,6 +805,10 @@ JL_DLLEXPORT jl_method_t *jl_new_method_uninit(jl_module_t *module)
     m->deleted_world = ~(size_t)0;
     m->is_for_opaque_closure = 0;
     m->constprop = 0;
+#ifdef JL_DISPATCH_LOG_BOXES
+    m->num_dynamic_dispatches = 0;
+    m->dynamic_dispatch_ns = 0;
+#endif
     JL_MUTEX_INIT(&m->writelock);
     return m;
 }
diff --git a/src/options.h b/src/options.h
index 06af3e33fcbdc..ec75e11b15307 100644
--- a/src/options.h
+++ b/src/options.h
@@ -98,6 +98,9 @@
 // profile generic (not inlined or specialized) calls to each function
 //#define JL_GF_PROFILE
 
+// count boxes and box sizes for generic calls
+#define JL_DISPATCH_LOG_BOXES
+
 
 // task options ---------------------------------------------------------------