--- a/jdk/src/java.base/share/classes/java/time/Duration.java	Wed Apr 13 09:20:22 2016 +0200
+++ b/jdk/src/java.base/share/classes/java/time/Duration.java	Wed Apr 13 10:41:27 2016 +0000
@@ -1350,6 +1350,48 @@
         return nanos;
     }
 
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns a copy of this {@code Duration} truncated to the specified unit.
+     * <p>
+     * Truncating the duration returns a copy of the original with conceptual fields
+     * smaller than the specified unit set to zero.
+     * For example, truncating with the {@link ChronoUnit#MINUTES MINUTES} unit will
+     * round down to the nearest minute, setting the seconds and nanoseconds to zero.
+     * <p>
+     * The unit must have a {@linkplain TemporalUnit#getDuration() duration}
+     * that divides into the length of a standard day without remainder.
+     * This includes all supplied time units on {@link ChronoUnit} and
+     * {@link ChronoUnit#DAYS DAYS}. Other ChronoUnits throw an exception.
+     * <p>
+     * This instance is immutable and unaffected by this method call.
+     *
+     * @param unit the unit to truncate to, not null
+     * @return a {@code Duration} based on this duration with the time truncated, not null
+     * @throws DateTimeException if the unit is invalid for truncation
+     * @throws UnsupportedTemporalTypeException if the unit is not supported
+     */
+    public Duration truncatedTo(TemporalUnit unit) {
+        Objects.requireNonNull(unit, "unit");
+        if (unit == ChronoUnit.SECONDS && (seconds >= 0 || nanos == 0)) {
+            return new Duration(seconds, 0);
+        } else if (unit == ChronoUnit.NANOS) {
+            return this;
+        }
+        Duration unitDur = unit.getDuration();
+        if (unitDur.getSeconds() > LocalTime.SECONDS_PER_DAY) {
+            throw new UnsupportedTemporalTypeException("Unit is too large to be used for truncation");
+        }
+        long dur = unitDur.toNanos();
+        if ((LocalTime.NANOS_PER_DAY % dur) != 0) {
+            throw new UnsupportedTemporalTypeException("Unit must divide into a standard day without remainder");
+        }
+        long nod = (seconds % LocalTime.SECONDS_PER_DAY) * LocalTime.NANOS_PER_SECOND + nanos;
+        long result = (nod / dur) * dur ;
+        return plusNanos(result - nod);
+    }
+
     //-----------------------------------------------------------------------
     /**
      * Compares this duration to the specified {@code Duration}.

--- a/jdk/test/java/time/tck/java/time/TCKDuration.java	Wed Apr 13 09:20:22 2016 +0200
+++ b/jdk/test/java/time/tck/java/time/TCKDuration.java	Wed Apr 13 10:41:27 2016 +0000
@@ -65,9 +65,11 @@
 import static java.time.temporal.ChronoUnit.MICROS;
 import static java.time.temporal.ChronoUnit.MILLIS;
 import static java.time.temporal.ChronoUnit.MINUTES;
+import static java.time.temporal.ChronoUnit.MONTHS;
 import static java.time.temporal.ChronoUnit.NANOS;
 import static java.time.temporal.ChronoUnit.SECONDS;
 import static java.time.temporal.ChronoUnit.WEEKS;
+import static java.time.temporal.ChronoUnit.YEARS;
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.assertTrue;
 import static org.testng.Assert.fail;
@@ -2287,6 +2289,133 @@
     }
 
     //-----------------------------------------------------------------------
+    //  truncated(TemporalUnit)
+    //-----------------------------------------------------------------------
+    TemporalUnit NINETY_MINS = new TemporalUnit() {
+        @Override
+        public Duration getDuration() {
+            return Duration.ofMinutes(90);
+        }
+        @Override
+        public boolean isDurationEstimated() {
+            return false;
+        }
+        @Override
+        public boolean isDateBased() {
+            return false;
+        }
+        @Override
+        public boolean isTimeBased() {
+            return true;
+        }
+        @Override
+        public boolean isSupportedBy(Temporal temporal) {
+            return false;
+        }
+        @Override
+        public <R extends Temporal> R addTo(R temporal, long amount) {
+            throw new UnsupportedOperationException();
+        }
+        @Override
+        public long between(Temporal temporal1, Temporal temporal2) {
+            throw new UnsupportedOperationException();
+        }
+        @Override
+        public String toString() {
+            return "NinetyMins";
+        }
+    };
+
+    TemporalUnit NINETY_FIVE_MINS = new TemporalUnit() {
+        @Override
+        public Duration getDuration() {
+            return Duration.ofMinutes(95);
+        }
+        @Override
+        public boolean isDurationEstimated() {
+            return false;
+        }
+        @Override
+        public boolean isDateBased() {
+            return false;
+        }
+        @Override
+        public boolean isTimeBased() {
+            return false;
+        }
+        @Override
+        public boolean isSupportedBy(Temporal temporal) {
+            return false;
+        }
+        @Override
+        public <R extends Temporal> R addTo(R temporal, long amount) {
+            throw new UnsupportedOperationException();
+        }
+        @Override
+        public long between(Temporal temporal1, Temporal temporal2) {
+            throw new UnsupportedOperationException();
+        }
+        @Override
+        public String toString() {
+            return "NinetyFiveMins";
+        }
+    };
+
+    @DataProvider(name="truncatedToValid")
+    Object[][] data_truncatedToValid() {
+        return new Object[][] {
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), NANOS, Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789)},
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), MICROS, Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_000)},
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), MILLIS, Duration.ofSeconds(86400 + 3600 + 60 + 1, 1230_00_000)},
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), SECONDS, Duration.ofSeconds(86400 + 3600 + 60 + 1, 0)},
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), MINUTES, Duration.ofSeconds(86400 + 3600 + 60, 0)},
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), HOURS, Duration.ofSeconds(86400 + 3600, 0)},
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), DAYS, Duration.ofSeconds(86400, 0)},
+
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 123_456_789), NINETY_MINS, Duration.ofSeconds(86400 + 0, 0)},
+                {Duration.ofSeconds(86400 + 7200 + 60 + 1, 123_456_789), NINETY_MINS, Duration.ofSeconds(86400 + 5400, 0)},
+                {Duration.ofSeconds(86400 + 10800 + 60 + 1, 123_456_789), NINETY_MINS, Duration.ofSeconds(86400 + 10800, 0)},
+
+                {Duration.ofSeconds(-86400 - 3600 - 60 - 1, 123_456_789), MINUTES, Duration.ofSeconds(-86400 - 3600 - 60, 0 )},
+                {Duration.ofSeconds(-86400 - 3600 - 60 - 1, 123_456_789), MICROS, Duration.ofSeconds(-86400 - 3600 - 60 - 1, 123_457_000)},
+
+                {Duration.ofSeconds(86400 + 3600 + 60 + 1, 0), SECONDS, Duration.ofSeconds(86400 + 3600 + 60 + 1, 0)},
+                {Duration.ofSeconds(-86400 - 3600 - 120, 0), MINUTES, Duration.ofSeconds(-86400 - 3600 - 120, 0)},
+
+                {Duration.ofSeconds(-1, 0), SECONDS, Duration.ofSeconds(-1, 0)},
+                {Duration.ofSeconds(-1, 123_456_789), SECONDS, Duration.ofSeconds(0, 0)},
+                {Duration.ofSeconds(-1, 123_456_789), NANOS, Duration.ofSeconds(0, -876_543_211)},
+                {Duration.ofSeconds(0, 123_456_789), SECONDS, Duration.ofSeconds(0, 0)},
+                {Duration.ofSeconds(0, 123_456_789), NANOS, Duration.ofSeconds(0, 123_456_789)},
+        };
+    }
+
+    @Test(dataProvider="truncatedToValid")
+    public void test_truncatedTo_valid(Duration input, TemporalUnit unit, Duration expected) {
+        assertEquals(input.truncatedTo(unit), expected);
+    }
+
+    @DataProvider(name="truncatedToInvalid")
+    Object[][] data_truncatedToInvalid() {
+        return new Object[][] {
+                {Duration.ofSeconds(1, 123_456_789), NINETY_FIVE_MINS},
+                {Duration.ofSeconds(1, 123_456_789), WEEKS},
+                {Duration.ofSeconds(1, 123_456_789), MONTHS},
+                {Duration.ofSeconds(1, 123_456_789), YEARS},
+        };
+    }
+
+    @Test(dataProvider="truncatedToInvalid", expectedExceptions=DateTimeException.class)
+    public void test_truncatedTo_invalid(Duration input, TemporalUnit unit) {
+        input.truncatedTo(unit);
+    }
+
+    @Test(expectedExceptions=NullPointerException.class)
+    public void test_truncatedTo_null() {
+        Duration.ofSeconds(1234).truncatedTo(null);
+    }
+
+    //-----------------------------------------------------------------------
     // dividedBy()
     //-----------------------------------------------------------------------
     @DataProvider(name="DividedBy")