diff --git a/Zend/Optimizer/dfa_pass.c b/Zend/Optimizer/dfa_pass.c
index 3ed507c35b070..0f76566a171d5 100644
--- a/Zend/Optimizer/dfa_pass.c
+++ b/Zend/Optimizer/dfa_pass.c
@@ -38,7 +38,7 @@
 # include "ssa_integrity.c"
 #endif
 
-zend_result zend_dfa_analyze_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa)
+zend_result zend_dfa_analyze_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa, uint32_t *arg_types, HashTable *op_array_to_arg_offset)
 {
 	uint32_t build_flags;
 
@@ -95,7 +95,7 @@ zend_result zend_dfa_analyze_op_array(zend_op_array *op_array, zend_optimizer_ct
 
 	zend_ssa_find_sccs(op_array, ssa);
 
-	if (zend_ssa_inference(&ctx->arena, op_array, ctx->script, ssa, ctx->optimization_level) == FAILURE) {
+	if (zend_ssa_inference(&ctx->arena, op_array, ctx->script, ssa, ctx->optimization_level, arg_types, op_array_to_arg_offset) == FAILURE) {
 		return FAILURE;
 	}
 
@@ -1708,7 +1708,7 @@ void zend_optimize_dfa(zend_op_array *op_array, zend_optimizer_ctx *ctx)
 	void *checkpoint = zend_arena_checkpoint(ctx->arena);
 	zend_ssa ssa;
 
-	if (zend_dfa_analyze_op_array(op_array, ctx, &ssa) == FAILURE) {
+	if (zend_dfa_analyze_op_array(op_array, ctx, &ssa, NULL, 0) == FAILURE) {
 		zend_arena_release(&ctx->arena, checkpoint);
 		return;
 	}
diff --git a/Zend/Optimizer/zend_inference.c b/Zend/Optimizer/zend_inference.c
index afe1c2339ed3a..955716df82d65 100644
--- a/Zend/Optimizer/zend_inference.c
+++ b/Zend/Optimizer/zend_inference.c
@@ -4462,7 +4462,7 @@ static void zend_mark_cv_references(const zend_op_array *op_array, const zend_sc
 	free_alloca(worklist,  use_heap);
 }
 
-ZEND_API zend_result zend_ssa_inference(zend_arena **arena, const zend_op_array *op_array, const zend_script *script, zend_ssa *ssa, zend_long optimization_level) /* {{{ */
+ZEND_API zend_result zend_ssa_inference(zend_arena **arena, const zend_op_array *op_array, const zend_script *script, zend_ssa *ssa, zend_long optimization_level, uint32_t *arg_types, HashTable *op_array_to_arg_offset) /* {{{ */
 {
 	zend_ssa_var_info *ssa_var_info;
 	int i;
@@ -4499,6 +4499,63 @@ ZEND_API zend_result zend_ssa_inference(zend_arena **arena, const zend_op_array
 		return FAILURE;
 	}
 
+	if (arg_types && op_array->scope) {
+		const zend_func_info *func_info = ZEND_FUNC_INFO(op_array);
+		if (func_info) {
+			for (zend_call_info *callee_info = func_info->callee_info; callee_info != NULL; callee_info = callee_info->next_callee) {
+				const zend_op_array *callee_op_array = &callee_info->callee_func->op_array;
+
+				/* Only support argument type inference for user functions. */
+				if (callee_op_array->type != ZEND_USER_FUNCTION) {
+					continue;
+				}
+				/* Private functions can only be called from the class itself, and cannot be overridden.
+				 * Therefore, we know which argument types they can receive at compile time. */
+				if (!(callee_op_array->fn_flags & ZEND_ACC_PRIVATE)) {
+					continue;
+				}
+
+				const zval *arg_types_offset_zval = zend_hash_index_find(op_array_to_arg_offset, (zend_ulong) callee_op_array);
+				uint32_t arg_types_offset = Z_LVAL_P(arg_types_offset_zval);
+
+				/* Too complicated to handle here for now. */
+				if (callee_info->named_args || callee_info->num_args < callee_op_array->num_args || (callee_op_array->fn_flags & ZEND_ACC_VARIADIC)) {
+					/* If we already started inferring, clear those types. */
+					memset(arg_types + arg_types_offset, -1, callee_op_array->num_args * sizeof(uint32_t));
+					continue;
+				}
+				// fprintf(stderr, "callee info %p, %s\n", callee_info, callee_info->callee_func->common.function_name->val);
+
+				bool all_by_val = true;
+				for (uint32_t arg = 0; arg < callee_op_array->num_args && all_by_val; arg++) {
+					const zend_op *opline = callee_info->arg_info[arg].opline;
+					if (opline->opcode != ZEND_SEND_VAR && opline->opcode != ZEND_SEND_VAL) {
+						all_by_val = false;
+					}
+				}
+
+				if (all_by_val) {
+					for (uint32_t arg = 0; arg < callee_op_array->num_args; arg++) {
+						const zend_op *opline = callee_info->arg_info[arg].opline;
+						const zend_ssa_op *ssa_op = &ssa->ops[opline - op_array->opcodes];
+						uint32_t type;
+						if (opline->op1_type == IS_CONST) {
+							type = 1 << Z_TYPE_P(CRT_CONSTANT(opline->op1));
+						} else {
+							/* Note: if this has an op1_def, it's for refcounting purposes. */
+							ZEND_ASSERT(ssa_op->op1_use > -1);
+							type = ssa->var_info[ssa_op->op1_use].type & _ZEND_TYPE_MAY_BE_MASK;
+						}
+						arg_types[arg_types_offset + arg] |= type;
+					}
+				} else {
+					/* If we already started inferring, clear those types. */
+					memset(arg_types + arg_types_offset, -1, callee_op_array->num_args * sizeof(uint32_t));
+				}
+			}
+		}
+	}
+
 	return SUCCESS;
 }
 /* }}} */
diff --git a/Zend/Optimizer/zend_inference.h b/Zend/Optimizer/zend_inference.h
index 4e768c4f6d524..57095683d4e0b 100644
--- a/Zend/Optimizer/zend_inference.h
+++ b/Zend/Optimizer/zend_inference.h
@@ -220,7 +220,7 @@ BEGIN_EXTERN_C()
 
 ZEND_API void zend_ssa_find_false_dependencies(const zend_op_array *op_array, zend_ssa *ssa);
 ZEND_API void zend_ssa_find_sccs(const zend_op_array *op_array, zend_ssa *ssa);
-ZEND_API zend_result zend_ssa_inference(zend_arena **raena, const zend_op_array *op_array, const zend_script *script, zend_ssa *ssa, zend_long optimization_level);
+ZEND_API zend_result zend_ssa_inference(zend_arena **raena, const zend_op_array *op_array, const zend_script *script, zend_ssa *ssa, zend_long optimization_level, uint32_t *arg_types, HashTable *op_array_to_arg_offset);
 
 ZEND_API uint32_t zend_array_element_type(uint32_t t1, uint8_t op_type, int write, int insert);
 
diff --git a/Zend/Optimizer/zend_optimizer.c b/Zend/Optimizer/zend_optimizer.c
index 956a13d658399..d4c71edce4054 100644
--- a/Zend/Optimizer/zend_optimizer.c
+++ b/Zend/Optimizer/zend_optimizer.c
@@ -1466,6 +1466,18 @@ static void zend_optimizer_call_registered_passes(zend_script *script, void *ctx
 	}
 }
 
+static void zend_dfa_analysis_with_call_graph(zend_op_array *op_array, zend_optimizer_ctx *ctx, uint32_t *arg_types, HashTable *op_array_to_arg_offset)
+{
+	zend_func_info *func_info = ZEND_FUNC_INFO(op_array);
+	if (func_info) {
+		if (zend_dfa_analyze_op_array(op_array, ctx, &func_info->ssa, arg_types, op_array_to_arg_offset) == SUCCESS) {
+			func_info->flags = func_info->ssa.cfg.flags;
+		} else {
+			ZEND_SET_FUNC_INFO(op_array, NULL);
+		}
+	}
+}
+
 ZEND_API void zend_optimize_script(zend_script *script, zend_long optimization_level, zend_long debug_level)
 {
 	zend_op_array *op_array;
@@ -1505,17 +1517,54 @@ ZEND_API void zend_optimize_script(zend_script *script, zend_long optimization_l
 			}
 		}
 
+		/* Group all non-private methods first, they will be analyzed first, and their type inference info can be used
+		 * for private method arguments. */
+		int num_non_private_methods = 0;
+		uint32_t total_arg_count = 0;
+		zend_op_array **op_array_grouped = zend_arena_alloc(&ctx.arena, sizeof(zend_op_array *) * call_graph.op_arrays_count);
+		HashTable *op_array_to_arg_offset = zend_arena_alloc(&ctx.arena, sizeof(HashTable));
+		zend_hash_init(op_array_to_arg_offset, call_graph.op_arrays_count, NULL, NULL, false);
 		for (i = 0; i < call_graph.op_arrays_count; i++) {
-			func_info = ZEND_FUNC_INFO(call_graph.op_arrays[i]);
-			if (func_info) {
-				if (zend_dfa_analyze_op_array(call_graph.op_arrays[i], &ctx, &func_info->ssa) == SUCCESS) {
-					func_info->flags = func_info->ssa.cfg.flags;
-				} else {
-					ZEND_SET_FUNC_INFO(call_graph.op_arrays[i], NULL);
+			if (!(call_graph.op_arrays[i]->fn_flags & ZEND_ACC_PRIVATE)) {
+				num_non_private_methods++;
+			}
+			zval tmp;
+			ZVAL_LONG(&tmp, total_arg_count);
+			zend_hash_index_add_new(op_array_to_arg_offset, (zend_ulong) call_graph.op_arrays[i], &tmp);
+			total_arg_count += call_graph.op_arrays[i]->num_args;
+		}
+		uint32_t *arg_types = zend_arena_calloc(&ctx.arena, total_arg_count, sizeof(uint32_t));
+		int start_private_method_idx = num_non_private_methods;
+		int current_private_method_idx = start_private_method_idx;
+		for (i = 0; i < call_graph.op_arrays_count; i++) {
+			if (call_graph.op_arrays[i]->fn_flags & ZEND_ACC_PRIVATE) {
+				op_array_grouped[current_private_method_idx++] = call_graph.op_arrays[i];
+			} else {
+				op_array_grouped[--num_non_private_methods] = call_graph.op_arrays[i];
+			}
+		}
+
+		for (i = 0; i < start_private_method_idx; i++) {
+			zend_dfa_analysis_with_call_graph(op_array_grouped[i], &ctx, arg_types, op_array_to_arg_offset);
+		}
+
+		for (i = start_private_method_idx; i < call_graph.op_arrays_count; i++) {
+			zend_op_array *op_array = op_array_grouped[i];
+			const zval *arg_types_offset_zval = zend_hash_index_find(op_array_to_arg_offset, (zend_ulong) op_array);
+			uint32_t arg_types_offset = Z_LVAL_P(arg_types_offset_zval);
+
+			for (uint32_t arg = 0; arg < op_array->num_args; arg++) {
+				uint32_t inferred_type = arg_types[arg_types_offset + arg];
+				if (inferred_type != -1 && !ZEND_TYPE_IS_SET(op_array->arg_info[arg].type)) {
+					op_array->arg_info[arg].type.type_mask |= inferred_type;
 				}
 			}
+
+			zend_dfa_analysis_with_call_graph(op_array, &ctx, arg_types, op_array_to_arg_offset);
 		}
 
+		zend_hash_destroy(op_array_to_arg_offset);
+
 		//TODO: perform inner-script inference???
 		for (i = 0; i < call_graph.op_arrays_count; i++) {
 			func_info = ZEND_FUNC_INFO(call_graph.op_arrays[i]);
diff --git a/Zend/Optimizer/zend_optimizer_internal.h b/Zend/Optimizer/zend_optimizer_internal.h
index 2f708471ab1d5..a6cb5eed6ea23 100644
--- a/Zend/Optimizer/zend_optimizer_internal.h
+++ b/Zend/Optimizer/zend_optimizer_internal.h
@@ -111,7 +111,7 @@ void zend_optimizer_pass3(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimize_func_calls(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimize_cfg(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimize_dfa(zend_op_array *op_array, zend_optimizer_ctx *ctx);
-zend_result zend_dfa_analyze_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa);
+zend_result zend_dfa_analyze_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa, uint32_t *arg_types, HashTable *op_array_to_arg_offset);
 void zend_dfa_optimize_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa, zend_call_info **call_map);
 void zend_optimize_temporary_variables(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimizer_nop_removal(zend_op_array *op_array, zend_optimizer_ctx *ctx);
diff --git a/ext/opcache/jit/zend_jit.c b/ext/opcache/jit/zend_jit.c
index 874eff576b554..da158f6f40600 100644
--- a/ext/opcache/jit/zend_jit.c
+++ b/ext/opcache/jit/zend_jit.c
@@ -1363,7 +1363,7 @@ static int zend_jit_op_array_analyze2(const zend_op_array *op_array, zend_script
 	 && !(op_array->fn_flags & ZEND_ACC_GENERATOR)
 	 && !(ssa->cfg.flags & ZEND_FUNC_INDIRECT_VAR_ACCESS)) {
 		if (zend_ssa_inference(&CG(arena), op_array, script, ssa,
-				optimization_level & ~ZEND_OPTIMIZER_NARROW_TO_DOUBLE) != SUCCESS) {
+				optimization_level & ~ZEND_OPTIMIZER_NARROW_TO_DOUBLE, NULL, 0) != SUCCESS) {
 			return FAILURE;
 		}
 	}