diff --git a/mozilla/extensions/schema-validation/src/nsSchemaValidator.cpp b/mozilla/extensions/schema-validation/src/nsSchemaValidator.cpp
index f9c6c656a44..f62517ccc1e 100644
--- a/mozilla/extensions/schema-validation/src/nsSchemaValidator.cpp
+++ b/mozilla/extensions/schema-validation/src/nsSchemaValidator.cpp
@@ -2409,7 +2409,8 @@ nsSchemaValidator::ValidateBuiltinTypeTime(const nsAString & aValue,
     sprintf(fulldate, "22-AUG-1993 %d:%d:%d.%u", time.hour, time.minute,
             time.second, time.millisecond);
 
-    PR_ParseTimeString(fulldate, PR_TRUE, aResult);
+    PRBool isGMT = nsSchemaValidatorUtils::IsGMT(aValue);
+    PR_ParseTimeString(fulldate, isGMT ? PR_TRUE : PR_FALSE, aResult);
   } else {
     *aResult = nsnull;
     rv = NS_ERROR_ILLEGAL_VALUE;
@@ -2535,7 +2536,8 @@ nsSchemaValidator::ValidateBuiltinTypeDate(const nsAString & aValue,
     sprintf(fulldate, "%d-%s-%u 00:00:00", date.day,
             monthShorthand.get(), date.year);
 
-    PR_ParseTimeString(fulldate, PR_TRUE, aResult);
+    PRBool isGMT = nsSchemaValidatorUtils::IsGMT(aValue);
+    PR_ParseTimeString(fulldate, isGMT ? PR_TRUE : PR_FALSE, aResult);
   } else {
     *aResult = nsnull;
     rv = NS_ERROR_ILLEGAL_VALUE;
@@ -2622,7 +2624,8 @@ nsSchemaValidator::ValidateBuiltinTypeDateTime(const nsAString & aValue,
       dateTime.time.second,
       dateTime.time.millisecond);
 
-    PR_ParseTimeString(fulldate, PR_TRUE, aResult);
+    PRBool isGMT = nsSchemaValidatorUtils::IsGMT(aValue);
+    PR_ParseTimeString(fulldate, isGMT ? PR_TRUE : PR_FALSE, aResult);
   } else {
     *aResult = nsnull;
     rv = NS_ERROR_ILLEGAL_VALUE;
diff --git a/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.cpp b/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.cpp
index 040582d63a0..8adbf18fe20 100644
--- a/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.cpp
+++ b/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.cpp
@@ -2012,3 +2012,16 @@ nsSchemaValidatorUtils::FindCharInSet(const nsAString & aString,
   return kNotFound;
 }
 
+PRBool
+nsSchemaValidatorUtils::IsGMT(const nsAString & aDateTime)
+{
+  if (!aDateTime.IsEmpty()) {
+    PRInt32 end = aDateTime.Length() - 1;
+    PRUnichar c = aDateTime.CharAt(end);
+    if (c == 'Z') {
+      return PR_TRUE;
+    }
+  }
+
+  return PR_FALSE;
+}
diff --git a/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.h b/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.h
index 0cafeb72273..6eaf684c5e4 100644
--- a/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.h
+++ b/mozilla/extensions/schema-validation/src/nsSchemaValidatorUtils.h
@@ -243,6 +243,13 @@ public:
   static void SetToNullOrElement(nsIDOMNode *aNode, nsIDOMNode **aResultNode);
   static PRInt32 FindCharInSet(const nsAString & aString, const char *aSet,
                                PRInt32 aOffset = 0);
+  /**
+   * Determine if an xsd:date, xsd:dateTime, or xsd:time string
+   * represents a GMT (aka UTC) time. This function assumes the
+   * aDateTime string has already been validated.
+   */
+  static PRBool IsGMT(const nsAString & aDateTime);
+
 private:
   nsSchemaValidatorUtils();
   ~nsSchemaValidatorUtils();