diff --git a/src/relative-time.js b/src/relative-time.js
index 35c712a..3147563 100644
--- a/src/relative-time.js
+++ b/src/relative-time.js
@@ -1,6 +1,6 @@
 /* @flow strict */
 
-import {strftime, makeFormatter, isDayFirst, isThisYear, isYearSeparator} from './utils'
+import {strftime, makeFormatter, makeRelativeFormatter, isDayFirst, isThisYear, isYearSeparator} from './utils'
 
 export default class RelativeTime {
   date: Date
@@ -62,31 +62,29 @@ export default class RelativeTime {
     const month = Math.round(day / 30)
     const year = Math.round(month / 12)
     if (ms < 0) {
-      return 'just now'
+      return formatRelativeTime(0, 'second')
     } else if (sec < 10) {
-      return 'just now'
+      return formatRelativeTime(0, 'second')
     } else if (sec < 45) {
-      return `${sec} seconds ago`
+      return formatRelativeTime(-sec, 'second')
     } else if (sec < 90) {
-      return 'a minute ago'
+      return formatRelativeTime(-min, 'minute')
     } else if (min < 45) {
-      return `${min} minutes ago`
+      return formatRelativeTime(-min, 'minute')
     } else if (min < 90) {
-      return 'an hour ago'
+      return formatRelativeTime(-hr, 'hour')
     } else if (hr < 24) {
-      return `${hr} hours ago`
+      return formatRelativeTime(-hr, 'hour')
     } else if (hr < 36) {
-      return 'a day ago'
+      return formatRelativeTime(-day, 'day')
     } else if (day < 30) {
-      return `${day} days ago`
+      return formatRelativeTime(-day, 'day')
     } else if (day < 45) {
-      return 'a month ago'
-    } else if (month < 12) {
-      return `${month} months ago`
+      return formatRelativeTime(-month, 'month')
     } else if (month < 18) {
-      return 'a year ago'
+      return formatRelativeTime(-year, 'year')
     } else {
-      return `${year} years ago`
+      return formatRelativeTime(-year, 'year')
     }
   }
 
@@ -124,29 +122,29 @@ export default class RelativeTime {
     const month = Math.round(day / 30)
     const year = Math.round(month / 12)
     if (month >= 18) {
-      return `${year} years from now`
+      return formatRelativeTime(year, 'year')
     } else if (month >= 12) {
-      return 'a year from now'
+      return formatRelativeTime(year, 'year')
     } else if (day >= 45) {
-      return `${month} months from now`
+      return formatRelativeTime(month, 'month')
     } else if (day >= 30) {
-      return 'a month from now'
+      return formatRelativeTime(month, 'month')
     } else if (hr >= 36) {
-      return `${day} days from now`
+      return formatRelativeTime(day, 'day')
     } else if (hr >= 24) {
-      return 'a day from now'
+      return formatRelativeTime(day, 'day')
     } else if (min >= 90) {
-      return `${hr} hours from now`
+      return formatRelativeTime(hr, 'hour')
     } else if (min >= 45) {
-      return 'an hour from now'
+      return formatRelativeTime(hr, 'hour')
     } else if (sec >= 90) {
-      return `${min} minutes from now`
+      return formatRelativeTime(min, 'minute')
     } else if (sec >= 45) {
-      return 'a minute from now'
+      return formatRelativeTime(min, 'minute')
     } else if (sec >= 10) {
-      return `${sec} seconds from now`
+      return formatRelativeTime(sec, 'second')
     } else {
-      return 'just now'
+      return formatRelativeTime(0, 'second')
     }
   }
 
@@ -189,4 +187,92 @@ export default class RelativeTime {
   }
 }
 
+function formatRelativeTime(value: number, unit: string): string {
+  const formatter = relativeFormatter()
+  if (formatter) {
+    return formatter.format(value, unit)
+  } else {
+    return formatEnRelativeTime(value, unit)
+  }
+}
+
+// Simplified "en" RelativeTimeFormat.format function
+//
+// Values should roughly match
+//   new Intl.RelativeTimeFormat('en', {numeric: 'auto'}).format(value, unit)
+//
+function formatEnRelativeTime(value: number, unit: string): string {
+  if (value === 0) {
+    switch (unit) {
+      case 'year':
+      case 'quarter':
+      case 'month':
+      case 'week':
+        return `this ${unit}`
+      case 'day':
+        return 'today'
+      case 'hour':
+      case 'minute':
+        return `in 0 ${unit}s`
+      case 'second':
+        return 'now'
+    }
+  } else if (value === 1) {
+    switch (unit) {
+      case 'year':
+      case 'quarter':
+      case 'month':
+      case 'week':
+        return `next ${unit}`
+      case 'day':
+        return 'tomorrow'
+      case 'hour':
+      case 'minute':
+      case 'second':
+        return `in 1 ${unit}`
+    }
+  } else if (value === -1) {
+    switch (unit) {
+      case 'year':
+      case 'quarter':
+      case 'month':
+      case 'week':
+        return `last ${unit}`
+      case 'day':
+        return 'yesterday'
+      case 'hour':
+      case 'minute':
+      case 'second':
+        return `1 ${unit} ago`
+    }
+  } else if (value > 1) {
+    switch (unit) {
+      case 'year':
+      case 'quarter':
+      case 'month':
+      case 'week':
+      case 'day':
+      case 'hour':
+      case 'minute':
+      case 'second':
+        return `in ${value} ${unit}s`
+    }
+  } else if (value < -1) {
+    switch (unit) {
+      case 'year':
+      case 'quarter':
+      case 'month':
+      case 'week':
+      case 'day':
+      case 'hour':
+      case 'minute':
+      case 'second':
+        return `${-value} ${unit}s ago`
+    }
+  }
+
+  throw new RangeError(`Invalid unit argument for format() '${unit}'`)
+}
+
 const timeFormatter = makeFormatter({hour: 'numeric', minute: '2-digit'})
+const relativeFormatter = makeRelativeFormatter({numeric: 'auto'})
diff --git a/src/utils.js b/src/utils.js
index b97bb20..8e49bf3 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -164,3 +164,23 @@ export function isThisYear(date: Date) {
   const now = new Date()
   return now.getUTCFullYear() === date.getUTCFullYear()
 }
+
+// eslint-disable-next-line flowtype/no-weak-types
+export function makeRelativeFormatter(options: any): () => ?any {
+  let format
+  return function() {
+    if (format) return format
+    if ('Intl' in window && 'RelativeTimeFormat' in window.Intl) {
+      try {
+        // eslint-disable-next-line flowtype/no-flow-fix-me-comments
+        // $FlowFixMe: missing RelativeTimeFormat type
+        format = new Intl.RelativeTimeFormat(undefined, options)
+        return format
+      } catch (e) {
+        if (!(e instanceof RangeError)) {
+          throw e
+        }
+      }
+    }
+  }
+}
diff --git a/test/relative-time.js b/test/relative-time.js
index d9eeb43..57f8835 100644
--- a/test/relative-time.js
+++ b/test/relative-time.js
@@ -10,14 +10,14 @@ suite('relative-time', function() {
     const now = new Date(Date.now() + 3 * 60 * 60 * 24 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, '3 days from now')
+    assert.equal(time.textContent, 'in 3 days')
   })
 
-  test('rewrites from now past datetime to a day ago', function() {
+  test('rewrites from now past datetime to yesterday', function() {
     const now = new Date(Date.now() - 1 * 60 * 60 * 24 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'a day ago')
+    assert.equal(time.textContent, 'yesterday')
   })
 
   test('rewrites from now past datetime to hours ago', function() {
@@ -31,14 +31,14 @@ suite('relative-time', function() {
     const now = new Date(Date.now() + 3 * 60 * 60 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, '3 hours from now')
+    assert.equal(time.textContent, 'in 3 hours')
   })
 
   test('rewrites from now past datetime to an hour ago', function() {
     const now = new Date(Date.now() - 1 * 60 * 60 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'an hour ago')
+    assert.equal(time.textContent, '1 hour ago')
   })
 
   test('rewrites from now past datetime to minutes ago', function() {
@@ -52,49 +52,49 @@ suite('relative-time', function() {
     const now = new Date(Date.now() + 3 * 60 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, '3 minutes from now')
+    assert.equal(time.textContent, 'in 3 minutes')
   })
 
   test('rewrites from now past datetime to a minute ago', function() {
     const now = new Date(Date.now() - 1 * 60 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'a minute ago')
+    assert.equal(time.textContent, '1 minute ago')
   })
 
-  test('rewrites a few seconds ago to just now', function() {
+  test('rewrites a few seconds ago to now', function() {
     const now = new Date().toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
-  test('rewrites a few seconds from now to just now', function() {
+  test('rewrites a few seconds from now to now', function() {
     const now = new Date().toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
-  test('displays future times as just now', function() {
+  test('displays future times as now', function() {
     const now = new Date(Date.now() + 3 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
-  test('displays a day ago', function() {
+  test('displays yesterday', function() {
     const now = new Date(Date.now() - 60 * 60 * 24 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'a day ago')
+    assert.equal(time.textContent, 'yesterday')
   })
 
   test('displays a day from now', function() {
     const now = new Date(Date.now() + 60 * 60 * 24 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'a day from now')
+    assert.equal(time.textContent, 'tomorrow')
   })
 
   test('displays 2 days ago', function() {
@@ -108,7 +108,7 @@ suite('relative-time', function() {
     const now = new Date(Date.now() + 2 * 60 * 60 * 24 * 1000).toISOString()
     const time = document.createElement('relative-time')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, '2 days from now')
+    assert.equal(time.textContent, 'in 2 days')
   })
 
   test('switches to dates after 30 past days', function() {
@@ -144,10 +144,10 @@ suite('relative-time', function() {
     const now = new Date().toISOString()
 
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
 
     time.removeAttribute('datetime')
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
   test('sets relative contents when parsed element is upgraded', function() {
@@ -157,6 +157,6 @@ suite('relative-time', function() {
     if ('CustomElements' in window) {
       window.CustomElements.upgradeSubtree(root)
     }
-    assert.equal(root.children[0].textContent, 'just now')
+    assert.equal(root.children[0].textContent, 'now')
   })
 })
diff --git a/test/time-ago.js b/test/time-ago.js
index abd7cd1..d1cc054 100644
--- a/test/time-ago.js
+++ b/test/time-ago.js
@@ -13,18 +13,18 @@ suite('time-ago', function() {
     assert.equal(time.textContent, '3 minutes ago')
   })
 
-  test('rewrites a few seconds ago to just now', function() {
+  test('rewrites a few seconds ago to now', function() {
     const now = new Date().toISOString()
     const time = document.createElement('time-ago')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
-  test('displays future times as just now', function() {
+  test('displays future times as now', function() {
     const now = new Date(Date.now() + 3 * 1000).toISOString()
     const time = document.createElement('time-ago')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
   test('sets relative contents when parsed element is upgraded', function() {
@@ -34,7 +34,7 @@ suite('time-ago', function() {
     if ('CustomElements' in window) {
       window.CustomElements.upgradeSubtree(root)
     }
-    assert.equal(root.children[0].textContent, 'just now')
+    assert.equal(root.children[0].textContent, 'now')
   })
 
   test('micro formats years', function() {
diff --git a/test/time-until.js b/test/time-until.js
index 97c1b0e..423e8d8 100644
--- a/test/time-until.js
+++ b/test/time-until.js
@@ -3,28 +3,28 @@ suite('time-until', function() {
     const now = new Date(Date.now() + 10 * 365 * 24 * 60 * 60 * 1000).toISOString()
     const time = document.createElement('time-until')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, '10 years from now')
+    assert.equal(time.textContent, 'in 10 years')
   })
 
   test('rewrites from now future datetime to minutes ago', function() {
     const now = new Date(Date.now() + 3 * 60 * 1000).toISOString()
     const time = document.createElement('time-until')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, '3 minutes from now')
+    assert.equal(time.textContent, 'in 3 minutes')
   })
 
-  test('rewrites a few seconds from now to just now', function() {
+  test('rewrites a few seconds from now to now', function() {
     const now = new Date().toISOString()
     const time = document.createElement('time-until')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
-  test('displays past times as just now', function() {
+  test('displays past times as now', function() {
     const now = new Date(Date.now() + 3 * 1000).toISOString()
     const time = document.createElement('time-until')
     time.setAttribute('datetime', now)
-    assert.equal(time.textContent, 'just now')
+    assert.equal(time.textContent, 'now')
   })
 
   test('sets relative contents when parsed element is upgraded', function() {
@@ -34,7 +34,7 @@ suite('time-until', function() {
     if ('CustomElements' in window) {
       window.CustomElements.upgradeSubtree(root)
     }
-    assert.equal(root.children[0].textContent, 'just now')
+    assert.equal(root.children[0].textContent, 'now')
   })
 
   test('micro formats years', function() {