diff --git a/core/_preload.odin b/core/_preload.odin
index 5a778a0de..a46883fea 100644
--- a/core/_preload.odin
+++ b/core/_preload.odin
@@ -691,13 +691,6 @@ __dynamic_array_expr_error :: proc "contextless" (file: string, line, column: in
 	__debug_trap();
 }
 
-
-__substring_expr_error :: proc "contextless" (file: string, line, column: int, low, high: int) {
-	if 0 <= low && low <= high do return;
-	fmt.fprintf(os.stderr, "%s(%d:%d) Invalid substring indices: %d..%d\n",
-	            file, line, column, low, high);
-	__debug_trap();
-}
 __type_assertion_check :: proc "contextless" (ok: bool, file: string, line, column: int, from, to: ^Type_Info) {
 	if ok do return;
 	fmt.fprintf(os.stderr, "%s(%d:%d) Invalid type_assertion from %T to %T\n",
@@ -715,9 +708,6 @@ __bounds_check_error_loc :: inline proc "contextless" (using loc := #caller_loca
 __slice_expr_error_loc :: inline proc "contextless" (using loc := #caller_location, low, high: int) {
 	__slice_expr_error(file_path, int(line), int(column), low, high);
 }
-__substring_expr_error_loc :: inline proc "contextless" (using loc := #caller_location, low, high: int) {
-	__substring_expr_error(file_path, int(line), int(column), low, high);
-}
 
 __mem_set :: proc "contextless" (data: rawptr, value: i32, len: int) -> rawptr {
 	if data == nil do return nil;
diff --git a/examples/demo.odin b/examples/demo.odin
index 6461ba5da..617d289eb 100644
--- a/examples/demo.odin
+++ b/examples/demo.odin
@@ -19,6 +19,7 @@ when ODIN_OS == "windows" {
 	import win32 "core:sys/windows.odin"
 }
 
+@(link_name="general_stuff")
 general_stuff :: proc() {
 	fmt.println("# general_stuff");
 	{ // `do` for inline statmes rather than block
@@ -367,11 +368,7 @@ parametric_polymorphism :: proc() {
 	}
 
 	copy_slice :: proc(dst, src: []$T) -> int {
-		n := min(len(dst), len(src));
-		if n > 0 {
-			mem.copy(&dst[0], &src[0], n*size_of(T));
-		}
-		return n;
+		return mem.copy(&dst[0], &src[0], n*size_of(T));
 	}
 
 	double_params :: proc(a: $A, b: $B) -> A {
@@ -662,21 +659,21 @@ named_proc_parameters :: proc() {
 		b = 567;
 		return b, a;
 	}
-	fmt.println("foo0 =", foo0());
-	fmt.println("foo1 =", foo1());
-	fmt.println("foo2 =", foo2());
+	fmt.println("foo0 =", foo0()); // 123
+	fmt.println("foo1 =", foo1()); // 123
+	fmt.println("foo2 =", foo2()); // 567 321
 }
 
 main :: proc() {
-	when false {
 		general_stuff();
 		default_struct_values();
+	when false {
 		union_type();
 		parametric_polymorphism();
 		threading_example();
 		array_programming();
+	}
 		using_in();
 		named_proc_parameters();
-	}
 }
 
diff --git a/src/build_settings.cpp b/src/build_settings.cpp
index 5948bd0f4..e0bc71949 100644
--- a/src/build_settings.cpp
+++ b/src/build_settings.cpp
@@ -23,6 +23,7 @@ struct BuildContext {
 	bool   show_timings;
 	bool   keep_temp_files;
 	bool   debug;
+	bool   no_bounds_check;
 
 	gbAffinity affinity;
 	isize      thread_count;
diff --git a/src/ir.cpp b/src/ir.cpp
index ecaa5bbd4..dae3e94d6 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -3585,6 +3585,9 @@ irValue *ir_emit_logical_binary_expr(irProcedure *proc, AstNode *expr) {
 
 
 void ir_emit_bounds_check(irProcedure *proc, Token token, irValue *index, irValue *len) {
+	if (build_context.no_bounds_check) {
+		return;
+	}
 	if ((proc->module->stmt_state_flags & StmtStateFlag_no_bounds_check) != 0) {
 		return;
 	}
@@ -3610,6 +3613,9 @@ void ir_emit_bounds_check(irProcedure *proc, Token token, irValue *index, irValu
 }
 
 void ir_emit_slice_bounds_check(irProcedure *proc, Token token, irValue *low, irValue *high, bool is_substring) {
+	if (build_context.no_bounds_check) {
+		return;
+	}
 	if ((proc->module->stmt_state_flags & StmtStateFlag_no_bounds_check) != 0) {
 		return;
 	}
@@ -3628,11 +3634,13 @@ void ir_emit_slice_bounds_check(irProcedure *proc, Token token, irValue *low, ir
 	args[3] = low;
 	args[4] = high;
 
-	char const *func = is_substring ? "__substring_expr_error" : "__slice_expr_error";
-	ir_emit_global_call(proc, func, args, 5);
+	ir_emit_global_call(proc, "__slice_expr_error", args, 5);
 }
 
 void ir_emit_dynamic_array_bounds_check(irProcedure *proc, Token token, irValue *low, irValue *high, irValue *max) {
+	if (build_context.no_bounds_check) {
+		return;
+	}
 	if ((proc->module->stmt_state_flags & StmtStateFlag_no_bounds_check) != 0) {
 		return;
 	}
diff --git a/src/main.cpp b/src/main.cpp
index a31821e9b..ec9d8b768 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -212,6 +212,7 @@ enum BuildFlagKind {
 	BuildFlag_Debug,
 	BuildFlag_CrossCompile,
 	BuildFlag_CrossLibDir,
+	BuildFlag_NoBoundsCheck,
 
 	BuildFlag_COUNT,
 };
@@ -250,6 +251,7 @@ bool parse_build_flags(Array<String> args) {
 	add_flag(&build_flags, BuildFlag_Debug,             str_lit("debug"),           BuildFlagParam_None);
 	add_flag(&build_flags, BuildFlag_CrossCompile,      str_lit("cross-compile"),   BuildFlagParam_String);
 	add_flag(&build_flags, BuildFlag_CrossLibDir,       str_lit("cross-lib-dir"),   BuildFlagParam_String);
+	add_flag(&build_flags, BuildFlag_NoBoundsCheck,     str_lit("no-bounds-check"), BuildFlagParam_None);
 
 
 	GB_ASSERT(args.count >= 3);
@@ -505,6 +507,10 @@ bool parse_build_flags(Array<String> args) {
 						case BuildFlag_Debug:
 							build_context.debug = true;
 							break;
+
+						case BuildFlag_NoBoundsCheck:
+							build_context.no_bounds_check = true;
+							break;
 						}
 					}