diff --git a/beast/chrono/RelativeTime.h b/beast/chrono/RelativeTime.h
index 54da15daa..fbd60d3a3 100644
--- a/beast/chrono/RelativeTime.h
+++ b/beast/chrono/RelativeTime.h
@@ -60,6 +60,9 @@ public:
     /** Destructor. */
     ~RelativeTime() noexcept;
 
+    /** Returns the amount of time since the process was started. */
+    static RelativeTime fromStartup ();
+
     //==============================================================================
     /** Creates a new RelativeTime object representing a number of milliseconds.
         @see seconds, minutes, hours, days, weeks
@@ -145,41 +148,44 @@ public:
     String getDescription (const String& returnValueForZeroTime = "0") const;
     std::string to_string () const;
 
-    //==============================================================================
+    RelativeTime operator+ (double seconds) const noexcept
+        { return RelativeTime (numSeconds + seconds); }
+
+    RelativeTime operator- (double seconds) const noexcept
+        { return RelativeTime (numSeconds - seconds); }
+
     /** Adds another RelativeTime to this one. */
     RelativeTime operator+= (RelativeTime timeToAdd) noexcept;
+
     /** Subtracts another RelativeTime from this one. */
     RelativeTime operator-= (RelativeTime timeToSubtract) noexcept;
 
     /** Adds a number of seconds to this time. */
     RelativeTime operator+= (double secondsToAdd) noexcept;
+
     /** Subtracts a number of seconds from this time. */
     RelativeTime operator-= (double secondsToSubtract) noexcept;
 
 private:
-    //==============================================================================
     double numSeconds;
 };
 
-//==============================================================================
-/** Compares two RelativeTimes. */
+//------------------------------------------------------------------------------
+
 bool operator== (RelativeTime t1, RelativeTime t2) noexcept;
-/** Compares two RelativeTimes. */
 bool operator!= (RelativeTime t1, RelativeTime t2) noexcept;
-/** Compares two RelativeTimes. */
 bool operator>  (RelativeTime t1, RelativeTime t2) noexcept;
-/** Compares two RelativeTimes. */
 bool operator<  (RelativeTime t1, RelativeTime t2) noexcept;
-/** Compares two RelativeTimes. */
 bool operator>= (RelativeTime t1, RelativeTime t2) noexcept;
-/** Compares two RelativeTimes. */
 bool operator<= (RelativeTime t1, RelativeTime t2) noexcept;
 
-//==============================================================================
+//------------------------------------------------------------------------------
+
 /** Adds two RelativeTimes together. */
-RelativeTime  operator+  (RelativeTime t1, RelativeTime t2) noexcept;
+RelativeTime operator+ (RelativeTime t1, RelativeTime t2) noexcept;
+
 /** Subtracts two RelativeTimes. */
-RelativeTime  operator-  (RelativeTime t1, RelativeTime t2) noexcept;
+RelativeTime operator- (RelativeTime t1, RelativeTime t2) noexcept;
 
 inline std::ostream& operator<< (std::ostream& os, RelativeTime const& diff)
 {
@@ -190,4 +196,3 @@ inline std::ostream& operator<< (std::ostream& os, RelativeTime const& diff)
 }
 
 #endif
-
diff --git a/beast/chrono/impl/RelativeTime.cpp b/beast/chrono/impl/RelativeTime.cpp
index ac78d3994..97736945a 100644
--- a/beast/chrono/impl/RelativeTime.cpp
+++ b/beast/chrono/impl/RelativeTime.cpp
@@ -256,3 +256,71 @@ std::string RelativeTime::to_string () const
 }
 
 }
+
+#if BEAST_WINDOWS
+
+#include <Windows.h>
+
+namespace beast {
+
+RelativeTime RelativeTime::fromStartup ()
+{
+    ULONGLONG ticks (GetTickCount64());
+
+    return RelativeTime (ticks / 1000.0);
+}
+
+}
+
+#else
+
+#include <time.h>
+
+namespace beast {
+
+namespace detail {
+
+// Converts a timespec to a RelativeTme
+static RelativeTime toRelativeTime (timespec const& ts)
+{
+    return RelativeTime (ts.tv_sec +
+        ts.tv_nsec / 1000000000.0);
+}
+
+// Records and returns the time from process startup
+static RelativeTime getStartupTime()
+{
+    struct StartupTime
+    {
+        StartupTime ()
+            { clock_gettime (CLOCK_MONOTONIC, &ts); }
+        timespec ts;
+    };
+
+    static StartupTime startupTime;
+
+    return toRelativeTime (startupTime.ts);
+}
+
+// Used to call getStartupTime as early as possible
+struct StartupTimeStaticInitializer
+{
+    StartupTimeStaticInitializer ()
+        { getStartupTime(); }
+};
+
+static StartupTimeStaticInitializer startupTimeStaticInitializer;
+
+}
+
+RelativeTime RelativeTime::fromStartup ()
+{
+    timespec ts;
+    clock_gettime (CLOCK_MONOTONIC, &ts);
+
+    return detail::toRelativeTime (ts) - detail::getStartupTime();
+}
+
+}
+
+#endif