diff --git a/src/arguments.c b/src/arguments.c
index 34efb8d..b6c9171 100644
--- a/src/arguments.c
+++ b/src/arguments.c
@@ -10,6 +10,7 @@ enum TdoError tdo_arguments_parse(struct TdoArguments *args, int argc, char **ar
     enum TdoError result = TDO_ERROR_OK;
     *args = (struct TdoArguments) {
         .processes = 1,
+        .time_limit = 5.0,
         .single_test = NULL,
         .test_file = NULL,
         .output = NULL,
@@ -78,6 +79,30 @@ enum TdoError tdo_arguments_parse(struct TdoArguments *args, int argc, char **ar
                     argc -= 1; argv += 1;
                     args->internal_status = argv[0];
                 }
+            } else if (strncmp(s, "--timeout", 10) == 0) {
+                if (argc <= 1) {
+                    fprintf(stderr, "Missing timeout argument\n");
+                    result = TDO_ERROR_ARG_PARSE;
+                } else {
+                    argc -= 1; argv += 1;
+                    char const *timeout_str = argv[0];
+
+                    errno = 0;
+                    char *err;
+                    float timeout = strtof(timeout_str, &err);
+                    if (errno) {
+                        perror("Could not parse amount of processes");
+                        result = TDO_ERROR_ARG_PARSE;
+                    } else if (*err != '\0') {
+                        fprintf(stderr, "Could not parse amount of threads: '%s'\n", timeout_str);
+                        result = TDO_ERROR_ARG_PARSE;
+                    } else if (timeout <= 0) {
+                        fprintf(stderr, "Amount of processes must be strictly positive, got %f\n", timeout);
+                        result = TDO_ERROR_ARG_PARSE;
+                    } else {
+                        args->time_limit = timeout;
+                    }
+                }
             } else {
                 fprintf(stderr, "Unrecognized argument: '%s'\n", s);
                 result = TDO_ERROR_ARG_PARSE;
diff --git a/src/arguments.h b/src/arguments.h
index 4303bde..2bc7e80 100644
--- a/src/arguments.h
+++ b/src/arguments.h
@@ -8,6 +8,7 @@
 
 struct TdoArguments {
     size_t processes;
+    float time_limit;
     char const *single_test;
     char const *test_file;
     char const *output;
diff --git a/src/platform/run_posix.c b/src/platform/run_posix.c
index 7a1a792..2838dd9 100644
--- a/src/platform/run_posix.c
+++ b/src/platform/run_posix.c
@@ -10,6 +10,7 @@
 #include <poll.h>
 #include <fcntl.h>
 #include <sys/wait.h>
+#include <signal.h>
 
 struct TdoRun {
     struct TdoTest *test;
@@ -187,7 +188,7 @@ void tdo_run_poll_exit(struct TdoRun *run, struct TdoRunStatus *status, struct T
 
         if (status->finished > 0) fprintf(output, ",");
         if (out_err == TDO_ERROR_OK && err_err == TDO_ERROR_OK && status_err == TDO_ERROR_OK)  {
-            tdo_run_report_status(run, arena, output, return_status, duration);
+            tdo_run_report_status(run, arena, output, return_status, duration, false);
         } else {
             tdo_run_report_error(*run->test, output, NULL, "could not read output", duration);
         }
@@ -262,10 +263,31 @@ void tdo_run_poll_event(struct TdoRunStatus *status, struct TdoArena *arena, str
         }
     }
     
+    struct timespec end_time = tdo_time_get();
+
     for (size_t i = 0; i < args.processes; i++) {
         struct TdoRun *run = &status->runs[i];
         if (run->active) {
             tdo_run_poll_exit(run, status, arena, output);
+            if (run->active) {
+                double duration = (
+                    (double)(end_time.tv_sec - run->start_time.tv_sec)
+                    + (double)(end_time.tv_nsec - run->start_time.tv_nsec) * 1e-9
+                );
+                if (duration > args.time_limit) {
+                    // timeout
+                    if (status->finished > 0) fprintf(output, ",");
+                    tdo_run_report_status(run, arena, output, 0, duration, true);
+
+                    kill(run->pid, SIGKILL);
+                    run->active = false;
+                    close(run->out.fd);
+                    close(run->err.fd);
+                    close(run->status.fd);
+                    status->running -= 1;
+                    status->finished += 1;
+                }
+            }
         }
     }
 }
diff --git a/src/platform/run_windows.c b/src/platform/run_windows.c
index 8fd4345..54d30f0 100644
--- a/src/platform/run_windows.c
+++ b/src/platform/run_windows.c
@@ -28,6 +28,7 @@ struct TdoRun {
     struct TdoString out_name;
     struct TdoString err_name;
     struct TdoString status_name;
+    bool timed_out;
     bool active;
     struct TdoOverlap out_ov;
     struct TdoOverlap err_ov;
@@ -255,6 +256,7 @@ void tdo_run_start_new(struct TdoRunStatus *status, struct TdoArena *arena, stru
     ResumeThread(pi.hThread);
     CloseHandle(pi.hThread);
 
+    run->timed_out = false;
     run->active = true;
     run->start_time = start_time;
     run->pid = pi.dwProcessId;
@@ -293,7 +295,7 @@ void tdo_run_maybe_report_exit(struct TdoArena *arena, struct TdoRun *run, struc
     double duration = (double)(end_time.QuadPart - run->start_time.QuadPart) / status->clock_frequency.QuadPart;
 
     if (status->finished > 0) fprintf(output, ",");
-    tdo_run_report_status(run, arena, output, run->exit_code, duration);
+    tdo_run_report_status(run, arena, output, run->exit_code, duration, run->timed_out);
 
     run->active = false;
     status->running -= 1;
@@ -301,7 +303,7 @@ void tdo_run_maybe_report_exit(struct TdoArena *arena, struct TdoRun *run, struc
 }
 
 void tdo_run_handle_exit(struct TdoArena *arena, struct TdoRun *run, struct TdoRunStatus *status, FILE *output, DWORD pid, DWORD msg) {
-    if (msg != JOB_OBJECT_MSG_EXIT_PROCESS) return;
+    if (msg != JOB_OBJECT_MSG_END_OF_PROCESS_TIME && msg != JOB_OBJECT_MSG_EXIT_PROCESS) return;
 
     if (run == NULL) {
         fprintf(stderr, "Process with unknown PID exited\n");
@@ -309,6 +311,14 @@ void tdo_run_handle_exit(struct TdoArena *arena, struct TdoRun *run, struct TdoR
         abort();
     }
 
+    if (msg == JOB_OBJECT_MSG_END_OF_PROCESS_TIME) {
+        run->timed_out = true;
+        CloseHandle(run->process_handle);
+        run->process_handle = NULL;
+        run->exit_code = 0;
+        return;
+    }
+
     DWORD return_status;
     if (!GetExitCodeProcess(run->process_handle, &return_status)) {
         fprintf(stderr, "Get exit code failed somehow... TODO: graceful exit\n");
@@ -556,7 +566,8 @@ enum TdoError tdo_run_status_init(struct TdoRunStatus *status, struct TdoArena *
     }
 
     JOBOBJECT_EXTENDED_LIMIT_INFORMATION jeli = {0};
-    jeli.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE;
+    jeli.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE | JOB_OBJECT_LIMIT_PROCESS_TIME;
+    jeli.BasicLimitInformation.PerProcessUserTimeLimit.QuadPart = (LONGLONG)(args.time_limit * 1e7);
 
     if (!SetInformationJobObject(status->job, JobObjectExtendedLimitInformation, &jeli, sizeof(jeli))) {
         result = TDO_ERROR_OS;
diff --git a/src/run.c b/src/run.c
index 63f2cc7..e32d43f 100644
--- a/src/run.c
+++ b/src/run.c
@@ -44,7 +44,7 @@ void tdo_log_dump(struct TdoLog log, FILE *file, char const *name) {
     fprintf(file, "\"");
 }
 
-void tdo_run_report_exit(struct TdoRun *run, FILE *file, char const *step, TdoProcessStatus status, double duration) {
+void tdo_run_report_exit(struct TdoRun *run, FILE *file, char const *step, TdoProcessStatus status, double duration, bool timed_out) {
     fprintf(file, "\n");
     fprintf(file, "\t{\n");
 
@@ -59,7 +59,9 @@ void tdo_run_report_exit(struct TdoRun *run, FILE *file, char const *step, TdoPr
     fprintf(file, "\t\t\"duration\": %lf,\n", duration);
 
     fprintf(file, "\t\t\"status\": \"");
-    if (tdo_process_status_is_exit(status)) {
+    if (timed_out) {
+        fprintf(file, "timeout");
+    } else if (tdo_process_status_is_exit(status)) {
         if (step[0] == 'f') {
             fprintf(file, "complete");
         } else {
@@ -72,15 +74,17 @@ void tdo_run_report_exit(struct TdoRun *run, FILE *file, char const *step, TdoPr
     }
     fprintf(file, "\"");
 
-    if (tdo_process_status_is_exit(status) && step[0] != 'f') {
-        fprintf(file, ",\n\t\t\"exit\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_exit(status));
-    } else if (tdo_process_status_is_signal(status)) {
-        fprintf(file, ",\n\t\t\"signal\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_signal(status));
-    } else if (tdo_process_status_is_stop(status)) {
-        fprintf(file, ",\n\t\t\"stop\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_stop(status));
+    if (!timed_out) {
+        if (tdo_process_status_is_exit(status) && step[0] != 'f') {
+            fprintf(file, ",\n\t\t\"exit\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_exit(status));
+        } else if (tdo_process_status_is_signal(status)) {
+            fprintf(file, ",\n\t\t\"signal\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_signal(status));
+        } else if (tdo_process_status_is_stop(status)) {
+            fprintf(file, ",\n\t\t\"stop\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_stop(status));
+        }
     }
 
-    if (step[0] != 'f') {
+    if (timed_out || step[0] != 'f') {
         fprintf(file, ",\n\t\t\"step\": \"");
         tdo_json_escaped(file, (struct TdoString) { .length=strlen(step), .bytes=(char*)step });
         fprintf(file, "\"");
@@ -123,6 +127,54 @@ void tdo_run_report_error(struct TdoTest test, FILE *file, char const *step, cha
     fprintf(file, "\t}");
 }
 
+void tdo_run_report_timeout(struct TdoRun *run, FILE *file, char const *step, TdoProcessStatus status, double duration) {
+    fprintf(file, "\n");
+    fprintf(file, "\t{\n");
+
+    fprintf(file, "\t\t\"file\": \"");
+    tdo_json_escaped(file, run->test->symbol.file->name);
+    fprintf(file, "\",\n");
+
+    fprintf(file, "\t\t\"name\": \"");
+    tdo_json_escaped(file, run->test->symbol.name);
+    fprintf(file, "\",\n");
+
+    fprintf(file, "\t\t\"duration\": %lf,\n", duration);
+
+    fprintf(file, "\t\t\"status\": \"");
+    if (tdo_process_status_is_exit(status)) {
+        if (step[0] == 'f') {
+            fprintf(file, "complete");
+        } else {
+            fprintf(file, "exit");
+        }
+    } else if (tdo_process_status_is_signal(status)) {
+        fprintf(file, "signal");
+    } else if (tdo_process_status_is_stop(status)) {
+        fprintf(file, "stop");
+    }
+    fprintf(file, "\"");
+
+    if (tdo_process_status_is_exit(status) && step[0] != 'f') {
+        fprintf(file, ",\n\t\t\"exit\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_exit(status));
+    } else if (tdo_process_status_is_signal(status)) {
+        fprintf(file, ",\n\t\t\"signal\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_signal(status));
+    } else if (tdo_process_status_is_stop(status)) {
+        fprintf(file, ",\n\t\t\"stop\": " TDO_PROCESS_CODE_FORMAT, tdo_process_code_stop(status));
+    }
+
+    if (step[0] != 'f') {
+        fprintf(file, ",\n\t\t\"step\": \"");
+        tdo_json_escaped(file, (struct TdoString) { .length=strlen(step), .bytes=(char*)step });
+        fprintf(file, "\"");
+    }
+
+    tdo_log_dump(run->out, file, "stdout");
+    tdo_log_dump(run->err, file, "stderr");
+
+    fprintf(file, "\n\t}");
+}
+
 enum TdoError tdo_string_previous_line(struct TdoString *line, struct TdoString string, size_t index) {
     if (string.bytes == NULL || string.length == 0) return TDO_ERROR_EOF;
     if (string.bytes[index] != '\n') return TDO_ERROR_NEWLINE;
@@ -195,7 +247,7 @@ enum TdoError tdo_run_report_assemble_step(struct TdoString *step, struct TdoAre
     return TDO_ERROR_OK;
 }
 
-void tdo_run_report_status(struct TdoRun *run, struct TdoArena *arena, FILE *file, int status, double duration) {
+void tdo_run_report_status(struct TdoRun *run, struct TdoArena *arena, FILE *file, int status, double duration, bool timed_out) {
     struct TdoArenaState state = tdo_arena_state_get(arena);
 
     struct TdoString log_status = run->status.data;
@@ -302,7 +354,7 @@ void tdo_run_report_status(struct TdoRun *run, struct TdoArena *arena, FILE *fil
             goto done;
         }
 
-        tdo_run_report_exit(run, file, step.bytes, status, duration);
+        tdo_run_report_exit(run, file, step.bytes, status, duration, timed_out);
     } else if (strncmp(last_line.bytes, "test", 4) == 0) {
         struct TdoString step;
         enum TdoError err_step = tdo_run_report_assemble_step(&step, arena, last_line, run->test->symbol);
@@ -312,10 +364,10 @@ void tdo_run_report_status(struct TdoRun *run, struct TdoArena *arena, FILE *fil
         }
 
         // unexpected exit while running test
-        tdo_run_report_exit(run, file, step.bytes, status, duration);
+        tdo_run_report_exit(run, file, step.bytes, status, duration, timed_out);
     } else if (strncmp(last_line.bytes, "finished", 8) == 0) {
         // test finished normally
-        tdo_run_report_exit(run, file, last_line.bytes, status, duration);
+        tdo_run_report_exit(run, file, last_line.bytes, status, duration, timed_out);
     } else {
         // unknown status
         tdo_run_report_error(*run->test, file, NULL, "unknown error", duration);
diff --git a/src/run.h b/src/run.h
index 11ec878..48abe4d 100644
--- a/src/run.h
+++ b/src/run.h
@@ -12,8 +12,8 @@ enum TdoError tdo_parse_size_t(size_t *number, char const *string);
 
 enum TdoError tdo_run_report_assemble_step(struct TdoString *step, struct TdoArena *arena, struct TdoString step_name, struct TdoSymbol symbol);
 
-void tdo_run_report_status(struct TdoRun *run, struct TdoArena *arena, FILE *file, int status, double duration);
-void tdo_run_report_exit(struct TdoRun *run, FILE *file, char const *step, TdoProcessStatus status, double duration);
+void tdo_run_report_status(struct TdoRun *run, struct TdoArena *arena, FILE *file, int status, double duration, bool timed_out);
+void tdo_run_report_exit(struct TdoRun *run, FILE *file, char const *step, TdoProcessStatus status, double duration, bool timed_out);
 void tdo_run_report_error(struct TdoTest test, FILE *file, char const *step, char const *error, double duration);
 void tdo_status_error(FILE *file, char const *fmt, ...);
 
diff --git a/test/conftest.py b/test/conftest.py
index d7c2263..b390407 100644
--- a/test/conftest.py
+++ b/test/conftest.py
@@ -318,6 +318,11 @@ class ResultStop(ResultDone):
     stop: int
 
 
+@dataclasses.dataclass
+class ResultTimeout(ResultDone):
+    step: Step
+
+
 class Error(enum.Enum):
     ok = 0
     unknown = -1
@@ -408,6 +413,9 @@ def run(tests: str, executable: Optional[str] = None, args: Optional[List[Any]]
             elif status == 'stop':
                 keys = {'file', 'name', 'duration', 'status', 'stop', 'stdout', 'stderr', 'step'}
                 result_type = ResultStop
+            elif status == 'timeout':
+                keys = {'file', 'name', 'duration', 'status', 'stdout', 'stderr', 'step'}
+                result_type = ResultTimeout
             else:
                 raise ValueError(f'Invalid status: "{status}"')
 
diff --git a/test/library.c b/test/library.c
index 3bdb3db..260d386 100644
--- a/test/library.c
+++ b/test/library.c
@@ -29,3 +29,20 @@ EXPORT void test_early_exit(void) {
 EXPORT void test_aborts(void) {
     abort();
 }
+
+EXPORT void test_print_forever(void) {
+    while (1) {
+        fprintf(stdout, "I am printing forever!\n");
+    }
+}
+
+EXPORT void test_timeout(void) {
+    fprintf(stdout, "Some output\n"); fflush(stdout);
+    fprintf(stderr, "Some error\n"); fflush(stderr);
+
+    volatile unsigned int x = 0;
+    while (1) {
+        x++;
+    }
+}
+
diff --git a/test/test_runner.py b/test/test_runner.py
index 91bc00f..a61f7ab 100644
--- a/test/test_runner.py
+++ b/test/test_runner.py
@@ -1,5 +1,5 @@
 from typing import Any
-from conftest import ResultComplete, ResultError, ResultExit, ResultSignal, StepFixtureAfter, StepFixtureBefore, StepTest, RunTests, approx
+from conftest import ResultComplete, ResultError, ResultExit, ResultSignal, ResultTimeout, StepFixtureAfter, StepFixtureBefore, StepTest, RunTests, approx
 
 
 def test_success(library: str, run_tests: RunTests):
@@ -68,6 +68,38 @@ def test_early_exit(library: str, run_tests: RunTests):
     )]
 
 
+def test_timeout(library: str, run_tests: RunTests):
+    result, _ = run_tests(f"""
+        test::{library}::test_success
+        test::{library}::test_timeout
+        test::{library}::test_success
+    """, args=['--timeout', 0.1])
+    assert result == [
+        ResultComplete(
+            file=library,
+            name='test_success',
+            duration=approx(0.0, abs=100.0),
+            stdout='',
+            stderr='',
+        ),
+        ResultTimeout(
+            file=library,
+            name='test_timeout',
+            duration=approx(0.0, abs=100.0),
+            step=StepTest(file=library, name='test_timeout'),
+            stdout='Some output\n',
+            stderr='Some error\n',
+        ),
+        ResultComplete(
+            file=library,
+            name='test_success',
+            duration=approx(0.0, abs=100.0),
+            stdout='',
+            stderr='',
+        ),
+    ]
+
+
 def test_aborts(library: str, run_tests: RunTests):
     result, _ = run_tests(f'test::{library}::test_aborts')
     assert result == [ResultSignal(