diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index b9ff3bf1f..ae4f1ec30 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -5773,6 +5773,39 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		operand->type = t_i64;
 		break;
 
+	case BuiltinProc_count_ones:
+	case BuiltinProc_trailing_zeros:
+	case BuiltinProc_reverse_bits:
+	case BuiltinProc_byte_swap:
+		if (!build_context.use_llvm_api) {
+			error(ce->args[0], "%.*s is not supported on this backend", LIT(builtin_procs[id].name));
+			// continue anyway
+		}
+		{
+			Operand x = {};
+			check_expr(c, &x, ce->args[0]);
+			if (x.mode == Addressing_Invalid) {
+				return false;
+			}
+
+			if (id == BuiltinProc_byte_swap && (!is_type_integer_like(x.type) && !is_type_float(x.type))) {
+				gbString xts = type_to_string(x.type);
+				error(x.expr, "Values passed to %.*s must be an integer-like type (integer, boolean, enum, bit_set) or float, got %s", LIT(builtin_procs[id].name), xts);
+				gb_string_free(xts);
+			} else if (id != BuiltinProc_byte_swap && !is_type_integer_like(x.type)) {
+				gbString xts = type_to_string(x.type);
+				error(x.expr, "Values passed to %.*s must be an integer-like type (integer, boolean, enum, bit_set), got %s", LIT(builtin_procs[id].name), xts);
+				gb_string_free(xts);
+			} else if (x.type == t_llvm_bool) {
+				gbString xts = type_to_string(x.type);
+				error(x.expr, "Invalid type passed to %.*s, got %s", LIT(builtin_procs[id].name), xts);
+				gb_string_free(xts);
+			}
+			operand->mode = Addressing_Value;
+			operand->type = default_type(x.type);
+		}
+		break;
+
 	case BuiltinProc_atomic_fence:
 	case BuiltinProc_atomic_fence_acq:
 	case BuiltinProc_atomic_fence_rel:
@@ -5913,7 +5946,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		{
 			if (!build_context.use_llvm_api) {
 				error(ce->args[0], "%.*s is not supported on this backend", LIT(builtin_procs[id].name));
-				return false;
+				// continue anyway
 			}
 
 			Operand x = {};
@@ -5979,8 +6012,9 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 	case BuiltinProc_expect:
 		if (!build_context.use_llvm_api) {
 			error(ce->args[0], "%.*s is not supported on this backend", LIT(builtin_procs[id].name));
-			return false;
-		} else {
+			// continue anyway
+		}
+		{
 			Operand x = {};
 			Operand y = {};
 			check_expr(c, &x, ce->args[0]);
diff --git a/src/checker_builtin_procs.hpp b/src/checker_builtin_procs.hpp
index 19a9d841e..7f8fd5323 100644
--- a/src/checker_builtin_procs.hpp
+++ b/src/checker_builtin_procs.hpp
@@ -45,6 +45,11 @@ enum BuiltinProcId {
 	BuiltinProc_debug_trap,
 	BuiltinProc_read_cycle_counter,
 
+	BuiltinProc_count_ones,
+	BuiltinProc_trailing_zeros,
+	BuiltinProc_reverse_bits,
+	BuiltinProc_byte_swap,
+
 	BuiltinProc_volatile_store,
 	BuiltinProc_volatile_load,
 
@@ -254,6 +259,10 @@ gb_global BuiltinProc builtin_procs[BuiltinProc_COUNT] = {
 	{STR_LIT("debug_trap"),         0, false, Expr_Stmt, BuiltinProcPkg_intrinsics, /*diverging*/false},
 	{STR_LIT("read_cycle_counter"), 0, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 
+	{STR_LIT("count_ones"),     1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+	{STR_LIT("trailing_zeros"), 1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+	{STR_LIT("reverse_bits"),   1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+	{STR_LIT("byte_swap"),      1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 
 	{STR_LIT("volatile_store"),  2, false, Expr_Stmt, BuiltinProcPkg_intrinsics},
 	{STR_LIT("volatile_load"),   1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
diff --git a/src/llvm_backend.cpp b/src/llvm_backend.cpp
index a67078180..2e77d66f2 100644
--- a/src/llvm_backend.cpp
+++ b/src/llvm_backend.cpp
@@ -9077,6 +9077,88 @@ lbValue lb_build_builtin_proc(lbProcedure *p, Ast *expr, TypeAndValue const &tv,
 			return res;
 		}
 
+	case BuiltinProc_trailing_zeros:
+		{
+			lbValue x = lb_build_expr(p, ce->args[0]);
+			x = lb_emit_conv(p, x, tv.type);
+
+			char const *name = "llvm.cttz";
+			LLVMTypeRef types[1] = {lb_type(p->module, tv.type)};
+			unsigned id = LLVMLookupIntrinsicID(name, gb_strlen(name));
+			GB_ASSERT_MSG(id != 0, "Unable to find %s.%s", name, LLVMPrintTypeToString(types[0]));
+			LLVMValueRef ip = LLVMGetIntrinsicDeclaration(p->module->mod, id, types, gb_count_of(types));
+
+			LLVMValueRef args[2] = {};
+			args[0] = x.value;
+			args[1] = LLVMConstNull(LLVMInt1TypeInContext(p->module->ctx));
+
+			lbValue res = {};
+			res.value = LLVMBuildCall(p->builder, ip, args, gb_count_of(args), "");
+			res.type = tv.type;
+			return res;
+		}
+
+	case BuiltinProc_count_ones:
+	case BuiltinProc_reverse_bits:
+		{
+			lbValue x = lb_build_expr(p, ce->args[0]);
+			x = lb_emit_conv(p, x, tv.type);
+
+			char const *name = nullptr;
+			switch (id) {
+			case BuiltinProc_count_ones:     name = "llvm.ctpop";      break;
+			case BuiltinProc_reverse_bits:   name = "llvm.bitreverse"; break;
+			}
+			LLVMTypeRef types[1] = {lb_type(p->module, tv.type)};
+			unsigned id = LLVMLookupIntrinsicID(name, gb_strlen(name));
+			GB_ASSERT_MSG(id != 0, "Unable to find %s.%s", name, LLVMPrintTypeToString(types[0]));
+			LLVMValueRef ip = LLVMGetIntrinsicDeclaration(p->module->mod, id, types, gb_count_of(types));
+
+			LLVMValueRef args[1] = {};
+			args[0] = x.value;
+
+			lbValue res = {};
+			res.value = LLVMBuildCall(p->builder, ip, args, gb_count_of(args), "");
+			res.type = tv.type;
+			return res;
+		}
+
+	case BuiltinProc_byte_swap:
+		{
+			lbValue x = lb_build_expr(p, ce->args[0]);
+			x = lb_emit_conv(p, x, tv.type);
+			if (is_type_float(tv.type)) {
+				i64 sz = type_size_of(tv.type);
+				Type *integer_type = nullptr;
+				switch (sz) {
+				case 2: integer_type = t_u16; break;
+				case 4: integer_type = t_u32; break;
+				case 8: integer_type = t_u64; break;
+				}
+				GB_ASSERT(integer_type != nullptr);
+				x = lb_emit_transmute(p, x, integer_type);
+			}
+
+			char const *name = "llvm.bswap";
+			LLVMTypeRef types[1] = {lb_type(p->module, x.type)};
+			unsigned id = LLVMLookupIntrinsicID(name, gb_strlen(name));
+			GB_ASSERT_MSG(id != 0, "Unable to find %s.%s", name, LLVMPrintTypeToString(types[0]));
+			LLVMValueRef ip = LLVMGetIntrinsicDeclaration(p->module->mod, id, types, gb_count_of(types));
+
+			LLVMValueRef args[1] = {};
+			args[0] = x.value;
+
+			lbValue res = {};
+			res.value = LLVMBuildCall(p->builder, ip, args, gb_count_of(args), "");
+			res.type = x.type;
+
+			if (is_type_float(tv.type)) {
+				res = lb_emit_transmute(p, res, tv.type);
+			}
+			return res;
+		}
+
+
 	case BuiltinProc_atomic_fence:
 		LLVMBuildFence(p->builder, LLVMAtomicOrderingSequentiallyConsistent, false, "");
 		return {};