diff --git a/src/thread_timer.h b/src/thread_timer.h
new file mode 100644
index 0000000..eaf108e
--- /dev/null
+++ b/src/thread_timer.h
@@ -0,0 +1,69 @@
+#ifndef BENCHMARK_THREAD_TIMER_H
+#define BENCHMARK_THREAD_TIMER_H
+
+#include "check.h"
+#include "timers.h"
+
+namespace benchmark {
+namespace internal {
+
+class ThreadTimer {
+ public:
+  ThreadTimer() = default;
+
+  // Called by each thread
+  void StartTimer() {
+    running_ = true;
+    start_real_time_ = ChronoClockNow();
+    start_cpu_time_ = ThreadCPUUsage();
+  }
+
+  // Called by each thread
+  void StopTimer() {
+    CHECK(running_);
+    running_ = false;
+    real_time_used_ += ChronoClockNow() - start_real_time_;
+    // Floating point error can result in the subtraction producing a negative
+    // time. Guard against that.
+    cpu_time_used_ += std::max<double>(ThreadCPUUsage() - start_cpu_time_, 0);
+  }
+
+  // Called by each thread
+  void SetIterationTime(double seconds) { manual_time_used_ += seconds; }
+
+  bool running() const { return running_; }
+
+  // REQUIRES: timer is not running
+  double real_time_used() {
+    CHECK(!running_);
+    return real_time_used_;
+  }
+
+  // REQUIRES: timer is not running
+  double cpu_time_used() {
+    CHECK(!running_);
+    return cpu_time_used_;
+  }
+
+  // REQUIRES: timer is not running
+  double manual_time_used() {
+    CHECK(!running_);
+    return manual_time_used_;
+  }
+
+ private:
+  bool running_ = false;        // Is the timer running
+  double start_real_time_ = 0;  // If running_
+  double start_cpu_time_ = 0;   // If running_
+
+  // Accumulated time so far (does not contain current slice if running_)
+  double real_time_used_ = 0;
+  double cpu_time_used_ = 0;
+  // Manually set iteration time. User sets this with SetIterationTime(seconds).
+  double manual_time_used_ = 0;
+};
+
+}  // namespace internal
+}  // namespace benchmark
+
+#endif  // BENCHMARK_THREAD_TIMER_H