diff --git a/ee/app/assets/javascripts/roadmap/constants.js b/ee/app/assets/javascripts/roadmap/constants.js
index 9f4021f9d80ab5c492ae1459ea3126ace8e1a195..f50c5e9b4eaca9e7d1a95ce65d9463712a15c58a 100644
--- a/ee/app/assets/javascripts/roadmap/constants.js
+++ b/ee/app/assets/javascripts/roadmap/constants.js
@@ -42,3 +42,7 @@ export const PRESET_DEFAULTS = {
     TIMEFRAME_LENGTH: 7,
   },
 };
+
+export const PAST_DATE = new Date(new Date().getFullYear() - 100, 0, 1);
+
+export const FUTURE_DATE = new Date(new Date().getFullYear() + 100, 0, 1);
diff --git a/ee/app/assets/javascripts/roadmap/utils/roadmap_utils.js b/ee/app/assets/javascripts/roadmap/utils/roadmap_utils.js
index ffdaff4381d8ed1aaa064cff1c3824960e3786d0..e81597ca357358a4821935c4689e0399356ae314 100644
--- a/ee/app/assets/javascripts/roadmap/utils/roadmap_utils.js
+++ b/ee/app/assets/javascripts/roadmap/utils/roadmap_utils.js
@@ -6,6 +6,8 @@ import {
   EXTEND_AS,
   TIMELINE_CELL_MIN_WIDTH,
   DAYS_IN_WEEK,
+  PAST_DATE,
+  FUTURE_DATE,
 } from '../constants';
 
 const monthsForQuarters = {
@@ -408,45 +410,44 @@ export const getEpicsPathForPreset = ({
   return epicsPath;
 };
 
+/**
+ * This function takes two epics and return sortable dates depending on the '
+ * type of sorting order -- startDate or endDate.
+ */
+export function assignDates(a, b, { dateUndefined, outOfRange, originalDate, date, proxyDate }) {
+  let aDate;
+  let bDate;
+
+  if (a[dateUndefined]) {
+    // Set proxy date to be either far in the past or
+    // far in the future to ensure sort order is
+    // correct.
+    aDate = proxyDate;
+  } else {
+    aDate = a[outOfRange] ? a[originalDate] : a[date];
+  }
+
+  if (b[dateUndefined]) {
+    bDate = proxyDate;
+  } else {
+    bDate = b[outOfRange] ? b[originalDate] : b[date];
+  }
+
+  return [aDate, bDate];
+}
+
 export const sortEpics = (epics, sortedBy) => {
   const sortByStartDate = sortedBy.indexOf('start_date') > -1;
   const sortOrderAsc = sortedBy.indexOf('asc') > -1;
-  const pastDate = new Date(new Date().getFullYear() - 100, 0, 1);
-  const futureDate = new Date(new Date().getFullYear() + 100, 0, 1);
 
   epics.sort((a, b) => {
-    let aDate;
-    let bDate;
-
-    if (sortByStartDate) {
-      if (a.startDateUndefined) {
-        // Set proxy date to be far in the past
-        // to ensure sort order is correct.
-        aDate = pastDate;
-      } else {
-        aDate = a.startDateOutOfRange ? a.originalStartDate : a.startDate;
-      }
-
-      if (b.startDateUndefined) {
-        bDate = pastDate;
-      } else {
-        bDate = b.startDateOutOfRange ? b.originalStartDate : b.startDate;
-      }
-    } else {
-      if (a.endDateUndefined) {
-        // Set proxy date to be far into the future
-        // to ensure sort order is correct.
-        aDate = futureDate;
-      } else {
-        aDate = a.endDateOutOfRange ? a.originalEndDate : a.endDate;
-      }
-
-      if (b.endDateUndefined) {
-        bDate = futureDate;
-      } else {
-        bDate = b.endDateOutOfRange ? b.originalEndDate : b.endDate;
-      }
-    }
+    const [aDate, bDate] = assignDates(a, b, {
+      dateUndefined: sortByStartDate ? 'startDateUndefined' : 'endDateUndefined',
+      outOfRange: sortByStartDate ? 'startDateOutOfRange' : 'endDateOutOfRange',
+      originalDate: sortByStartDate ? 'originalStartDate' : 'originalEndDate',
+      date: sortByStartDate ? 'startDate' : 'endDate',
+      proxyDate: sortByStartDate ? PAST_DATE : FUTURE_DATE,
+    });
 
     // Sort in ascending or descending order
     if (aDate.getTime() < bDate.getTime()) {
diff --git a/ee/spec/javascripts/roadmap/utils/roadmap_utils_spec.js b/ee/spec/javascripts/roadmap/utils/roadmap_utils_spec.js
index 6806cd268ae364d4d3ca038ff737cce110f32e7e..555e6a1bce091c20d182a4d3fc02fc360b514960 100644
--- a/ee/spec/javascripts/roadmap/utils/roadmap_utils_spec.js
+++ b/ee/spec/javascripts/roadmap/utils/roadmap_utils_spec.js
@@ -8,6 +8,7 @@ import {
   extendTimeframeForAvailableWidth,
   getEpicsPathForPreset,
   sortEpics,
+  assignDates,
 } from 'ee/roadmap/utils/roadmap_utils';
 
 import { PRESET_TYPES } from 'ee/roadmap/constants';
@@ -434,3 +435,114 @@ describe('sortEpics', () => {
     });
   });
 });
+
+describe('assignDates', () => {
+  const startDateProps = {
+    dateUndefined: 'startDateUndefined',
+    outOfRange: 'startDateOutOfRange',
+    originalDate: 'originalStartDate',
+    date: 'startDate',
+    proxyDate: new Date('1900'),
+  };
+  const endDateProps = {
+    dateUndefined: 'endDateUndefined',
+    outOfRange: 'endDateOutOfRange',
+    originalDate: 'originalEndDate',
+    date: 'endDate',
+    proxyDate: new Date('2200'),
+  };
+
+  it('returns proxyDate if startDate is undefined', () => {
+    const epic1 = { startDateUndefined: true };
+    const epic2 = { startDateUndefined: false };
+
+    let [aDate, bDate] = assignDates(epic1, epic2, startDateProps);
+
+    expect(aDate).toEqual(startDateProps.proxyDate);
+    expect(bDate).not.toEqual(startDateProps.proxyDate);
+
+    epic1.startDateUndefined = false;
+    epic2.startDateUndefined = true;
+    [aDate, bDate] = assignDates(epic1, epic2, startDateProps);
+
+    expect(aDate).not.toEqual(startDateProps.proxyDate);
+    expect(bDate).toEqual(startDateProps.proxyDate);
+  });
+
+  it('returns proxyDate if endDate is undefined', () => {
+    const epic1 = { endDateUndefined: true };
+    const epic2 = { endDateUndefined: false };
+
+    let [aDate, bDate] = assignDates(epic1, epic2, endDateProps);
+
+    expect(aDate).toEqual(endDateProps.proxyDate);
+    expect(bDate).not.toEqual(endDateProps.proxyDate);
+
+    epic1.endDateUndefined = false;
+    epic2.endDateUndefined = true;
+    [aDate, bDate] = assignDates(epic1, epic2, endDateProps);
+
+    expect(aDate).not.toEqual(endDateProps.proxyDate);
+    expect(bDate).toEqual(endDateProps.proxyDate);
+  });
+
+  it('assigns originalStartDate if date is out of range', () => {
+    const epic1 = {
+      startDateUndefined: false,
+      originalStartDate: new Date('2000'),
+      startDate: new Date('2010'),
+      startDateOutOfRange: true,
+    };
+    const epic2 = { ...epic1, originalStartDate: new Date('2005') };
+
+    const [aDate, bDate] = assignDates(epic1, epic2, startDateProps);
+
+    expect(aDate).toEqual(epic1.originalStartDate);
+    expect(bDate).toEqual(epic2.originalStartDate);
+  });
+
+  it('assigns originalEndDate if date is out of range', () => {
+    const epic1 = {
+      endDateUndefined: false,
+      originalEndDate: new Date('2000'),
+      endDate: new Date('2010'),
+      endDateOutOfRange: true,
+    };
+    const epic2 = { ...epic1, originalEndDate: new Date('2005') };
+
+    const [aDate, bDate] = assignDates(epic1, epic2, endDateProps);
+
+    expect(aDate).toEqual(epic1.originalEndDate);
+    expect(bDate).toEqual(epic2.originalEndDate);
+  });
+
+  it('assigns startDate if date is in the range', () => {
+    const epic1 = {
+      startDateUndefined: false,
+      originalStartDate: new Date('2000'),
+      startDate: new Date('2010'),
+      startDateOutOfRange: false,
+    };
+    const epic2 = { ...epic1, startDate: new Date('2005') };
+
+    const [aDate, bDate] = assignDates(epic1, epic2, startDateProps);
+
+    expect(aDate).toEqual(epic1.startDate);
+    expect(bDate).toEqual(epic2.startDate);
+  });
+
+  it('assigns endDate if date is in the range', () => {
+    const epic1 = {
+      endDateUndefined: false,
+      originalEndDate: new Date('2000'),
+      endDate: new Date('2010'),
+      endDateOutOfRange: false,
+    };
+    const epic2 = { ...epic1, endDate: new Date('2005') };
+
+    const [aDate, bDate] = assignDates(epic1, epic2, endDateProps);
+
+    expect(aDate).toEqual(epic1.endDate);
+    expect(bDate).toEqual(epic2.endDate);
+  });
+});