diff --git a/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule.fs b/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule.fs
index 6047215fbb004dab39f0ce8df12221e570ab98cb..c7683abb5dfe68134efa2ca89854b0904f3ec9e7 100644
--- a/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule.fs
+++ b/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule.fs
@@ -199,6 +199,19 @@ type ArrayModule() =
         CheckThrowsInvalidOperationExn (fun () -> Array.take 5 [|"str1";"str2";"str3";"str4"|] |> ignore)
         CheckThrowsArgumentNullException (fun () -> Array.take 5 null |> ignore)
         
+    [<Test>]
+    member this.takeWhile() =
+        Assert.AreEqual([||],Array.takeWhile (fun x -> failwith "should not be used") [||])
+        Assert.AreEqual([|1;2;4;5|],Array.takeWhile (fun x -> x < 6) [|1;2;4;5;6;7|])
+        Assert.AreEqual([|"a"; "ab"; "abc"|],Array.takeWhile (fun (x:string) -> x.Length < 4) [|"a"; "ab"; "abc"; "abcd"; "abcde"|])
+        Assert.AreEqual([|"a"; "ab"; "abc"; "abcd"; "abcde"|],Array.takeWhile (fun _ -> true) [|"a"; "ab"; "abc"; "abcd"; "abcde"|])
+        Assert.AreEqual([||],Array.takeWhile (fun _ -> false) [|"a"; "ab"; "abc"; "abcd"; "abcde"|])
+        Assert.AreEqual([||],Array.takeWhile (fun _ -> false) [|"a"|])
+        Assert.AreEqual([|"a"|],Array.takeWhile (fun _ -> true) [|"a"|])
+        Assert.AreEqual([|"a"|],Array.takeWhile (fun x -> x <> "ab") [|"a"; "ab"; "abc"; "abcd"; "abcde"|])
+
+        CheckThrowsArgumentNullException (fun () -> Array.takeWhile (fun _ -> failwith "should not be used") null |> ignore) 
+        
     [<Test>]
     member this.Blit() = 
         // int array   
diff --git a/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ListModule.fs b/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ListModule.fs
index 45aacd0899330120bbcfb9672f365e8e706a8752..7c3cc03c08d33e0a22aee7c068a095024667475c 100644
--- a/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ListModule.fs
+++ b/src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ListModule.fs
@@ -180,7 +180,6 @@ type ListModule() =
         let emptyChosen = List.choose funcInt emptySrc        
         Assert.AreEqual(emptySrc, emptyChosen)
 
-        
         () 
 
     [<Test>]
@@ -203,6 +202,17 @@ type ListModule() =
         Assert.AreEqual(0,List.compareWith (fun x y -> 0) ["1";"2"] ["1";"3"])
         Assert.AreEqual(1,List.compareWith (fun x y -> 1) ["1";"2"] ["1";"3"])
         Assert.AreEqual(-1,List.compareWith (fun x y -> -1) ["1";"2"] ["1";"3"])
+        
+    [<Test>]
+    member this.takeWhile() =
+        Assert.AreEqual([],List.takeWhile (fun x -> failwith "should not be used") [])
+        Assert.AreEqual([1;2;4;5],List.takeWhile (fun x -> x < 6) [1;2;4;5;6;7])
+        Assert.AreEqual(["a"; "ab"; "abc"],List.takeWhile (fun (x:string) -> x.Length < 4) ["a"; "ab"; "abc"; "abcd"; "abcde"])        
+        Assert.AreEqual(["a"; "ab"; "abc"; "abcd"; "abcde"],List.takeWhile (fun _ -> true) ["a"; "ab"; "abc"; "abcd"; "abcde"])
+        Assert.AreEqual([],List.takeWhile (fun _ -> false) ["a"; "ab"; "abc"; "abcd"; "abcde"])
+        Assert.AreEqual([],List.takeWhile (fun _ -> false) ["a"])
+        Assert.AreEqual(["a"],List.takeWhile (fun _ -> true) ["a"])
+        Assert.AreEqual(["a"],List.takeWhile (fun x -> x <> "ab") ["a"; "ab"; "abc"; "abcd"; "abcde"])
 
     [<Test>]
     member this.Concat() =
diff --git a/src/fsharp/FSharp.Core.Unittests/SurfaceArea.4.0.fs b/src/fsharp/FSharp.Core.Unittests/SurfaceArea.4.0.fs
index 28bc044ff619f9032b152e7158404f90ec427734..eeed925887f075568ef84d8c7b710a5f1a532b5c 100644
--- a/src/fsharp/FSharp.Core.Unittests/SurfaceArea.4.0.fs
+++ b/src/fsharp/FSharp.Core.Unittests/SurfaceArea.4.0.fs
@@ -163,6 +163,7 @@ Microsoft.FSharp.Collections.ArrayModule: T[] Singleton[T](T)
 Microsoft.FSharp.Collections.ArrayModule: T[] SortBy[T,TKey](Microsoft.FSharp.Core.FSharpFunc`2[T,TKey], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] SortWith[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpFunc`2[T,System.Int32]], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] Sort[T](T[])
+Microsoft.FSharp.Collections.ArrayModule: T[] TakeWhile[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] Take[T](Int32, T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] Where[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] ZeroCreate[T](Int32)
@@ -306,6 +307,7 @@ Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] SortWith[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpFunc`2[T,System.Int32]], Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Sort[T](Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Tail[T](Microsoft.FSharp.Collections.FSharpList`1[T])
+Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] TakeWhile[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Take[T](Int32, Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Where[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Core.FSharpOption`1[System.Int32] TryFindIndex[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Collections.FSharpList`1[T])
diff --git a/src/fsharp/FSharp.Core.Unittests/SurfaceArea.Portable.fs b/src/fsharp/FSharp.Core.Unittests/SurfaceArea.Portable.fs
index 47b5fb73f96e53de602f411e80756f4384e0fa33..9565ca6a779e75c25791907e8a75f564fbb98171 100644
--- a/src/fsharp/FSharp.Core.Unittests/SurfaceArea.Portable.fs
+++ b/src/fsharp/FSharp.Core.Unittests/SurfaceArea.Portable.fs
@@ -157,6 +157,7 @@ Microsoft.FSharp.Collections.ArrayModule: T[] Singleton[T](T)
 Microsoft.FSharp.Collections.ArrayModule: T[] SortBy[T,TKey](Microsoft.FSharp.Core.FSharpFunc`2[T,TKey], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] SortWith[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpFunc`2[T,System.Int32]], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] Sort[T](T[])
+Microsoft.FSharp.Collections.ArrayModule: T[] TakeWhile[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] Take[T](Int32, T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] Where[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], T[])
 Microsoft.FSharp.Collections.ArrayModule: T[] ZeroCreate[T](Int32)
@@ -300,6 +301,7 @@ Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] SortWith[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpFunc`2[T,System.Int32]], Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Sort[T](Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Tail[T](Microsoft.FSharp.Collections.FSharpList`1[T])
+Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] TakeWhile[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Take[T](Int32, Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Collections.FSharpList`1[T] Where[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Collections.FSharpList`1[T])
 Microsoft.FSharp.Collections.ListModule: Microsoft.FSharp.Core.FSharpOption`1[System.Int32] TryFindIndex[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Collections.FSharpList`1[T])
diff --git a/src/fsharp/FSharp.Core/array.fs b/src/fsharp/FSharp.Core/array.fs
index c967977d20235666125a10a96576a8521e042a09..cfadbc2c99ff98f02dcc2692ddb9bef71f7c8232 100644
--- a/src/fsharp/FSharp.Core/array.fs
+++ b/src/fsharp/FSharp.Core/array.fs
@@ -120,6 +120,19 @@ namespace Microsoft.FSharp.Collections
             Array.Copy(array, 0, res, 0, count)
             res
 
+        [<CompiledName("TakeWhile")>]
+        let takeWhile predicate (array: 'T[]) = 
+            checkNonNull "array" array
+            if array.Length = 0 then empty else
+            let mutable count = 0
+            while count < array.Length && predicate array.[count] do
+                count <- count + 1
+
+            let res : 'T[] = Microsoft.FSharp.Primitives.Basics.Array.zeroCreateUnchecked count
+
+            Array.Copy(array, 0, res, 0, count)
+            res
+
         [<CompiledName("Append")>]
         let append (array1:'T[]) (array2:'T[]) = 
             checkNonNull "array1" array1
diff --git a/src/fsharp/FSharp.Core/array.fsi b/src/fsharp/FSharp.Core/array.fsi
index c11d2bcc3d215d4736db95187d88e5a7925ab25e..2bb426ce47c1dd7cbee7ecfc3f02df8fae66f2a0 100644
--- a/src/fsharp/FSharp.Core/array.fsi
+++ b/src/fsharp/FSharp.Core/array.fsi
@@ -657,6 +657,18 @@ namespace Microsoft.FSharp.Collections
         [<CompiledName("Take")>]
         val take: count:int -> array:'T[] -> 'T[]
 
+        /// <summary>Returns an array that contains all elements of the original array while the 
+        /// given predicate returns <c>true</c>, and then returns no further elements.</summary>
+        ///
+        /// <param name="predicate">A function that evaluates to false when no more items should be returned.</param>
+        /// <param name="array">The input array.</param>
+        ///
+        /// <returns>The result array.</returns>
+        ///
+        /// <exception cref="System.ArgumentNullException">Thrown when the input array is null.</exception>
+        [<CompiledName("TakeWhile")>]
+        val takeWhile: predicate:('T -> bool) -> array:'T[] -> 'T[]
+
         /// <summary>Builds a list from the given array.</summary>
         /// <param name="array">The input array.</param>
         /// <returns>The list of array elements.</returns>
diff --git a/src/fsharp/FSharp.Core/list.fs b/src/fsharp/FSharp.Core/list.fs
index f7b11c935173c2ceb58471c2eb77148b1edb7b78..488943445db206f5cbc326abdbaa589ee35a5e4b 100644
--- a/src/fsharp/FSharp.Core/list.fs
+++ b/src/fsharp/FSharp.Core/list.fs
@@ -90,6 +90,9 @@ namespace Microsoft.FSharp.Collections
         [<CompiledName("Take")>]
         let take count (list : 'T list) = Microsoft.FSharp.Primitives.Basics.List.take count list
 
+        [<CompiledName("TakeWhile")>]
+        let takeWhile p (list: 'T list) = Microsoft.FSharp.Primitives.Basics.List.takeWhile p list
+
         [<CompiledName("IterateIndexed")>]
         let iteri f list = Microsoft.FSharp.Primitives.Basics.List.iteri f list
 
diff --git a/src/fsharp/FSharp.Core/list.fsi b/src/fsharp/FSharp.Core/list.fsi
index cd62769b49025610487d63dd0d5a60f1b6f455a3..f9e8eecc70ba8279ef4d815998bd20432cabe04d 100644
--- a/src/fsharp/FSharp.Core/list.fsi
+++ b/src/fsharp/FSharp.Core/list.fsi
@@ -587,6 +587,16 @@ namespace Microsoft.FSharp.Collections
         [<CompiledName("Take")>]
         val take: count:int -> list:'T list -> 'T list
 
+        /// <summary>Returns a list that contains all elements of the original list while the 
+        /// given predicate returns <c>true</c>, and then returns no further elements.</summary>
+        ///
+        /// <param name="predicate">A function that evaluates to false when no more items should be returned.</param>
+        /// <param name="list">The input list.</param>
+        ///
+        /// <returns>The result list.</returns>
+        [<CompiledName("TakeWhile")>]
+        val takeWhile: predicate:('T -> bool) -> list:'T list -> 'T list
+
         /// <summary>Builds an array from the given list.</summary>
         /// <param name="list">The input list.</param>
         /// <returns>The array containing the elements of the list.</returns>
diff --git a/src/fsharp/FSharp.Core/local.fs b/src/fsharp/FSharp.Core/local.fs
index 7cec850f12266a77a38431dafeab381505bbf9c0..1a9dbc46519295e8b1bfdde45fa5beeec30bef43 100644
--- a/src/fsharp/FSharp.Core/local.fs
+++ b/src/fsharp/FSharp.Core/local.fs
@@ -466,6 +466,27 @@ module internal List =
             res <- arr.[i] :: res
         res
 
+    let rec takeWhileFreshConsTail cons p l =
+        match l with
+        | [] -> setFreshConsTail cons []
+        | x::xs ->
+            if p x then
+                let cons2 = freshConsNoTail x
+                setFreshConsTail cons cons2
+                takeWhileFreshConsTail cons2 p xs
+            else
+                setFreshConsTail cons []
+
+    let takeWhile p (l: 'T list) =
+        match l with
+        | [] -> l
+        | x :: ([] as nil) -> if p x then l else nil
+        | x::xs ->
+            if not (p x) then [] else
+            let cons = freshConsNoTail x
+            takeWhileFreshConsTail cons p xs
+            cons
+
     // NOTE: This implementation is now only used for List.sortWith. We should change that to use the stable sort via arrays
     // below, and remove this implementation.
     module StableSortImplementation =
diff --git a/src/fsharp/FSharp.Core/local.fsi b/src/fsharp/FSharp.Core/local.fsi
index 1a4261e9fbaa708d2331d6b1b3b9460b19f40849..c34ded83ba61f603ea1a9603269f3197832ee584 100644
--- a/src/fsharp/FSharp.Core/local.fsi
+++ b/src/fsharp/FSharp.Core/local.fsi
@@ -28,6 +28,7 @@ module internal List =
     val zip3 : 'T1 list -> 'T2 list -> 'T3 list -> ('T1 * 'T2 * 'T3) list
     val ofArray : 'T[] -> 'T list
     val take : int -> 'T list -> 'T list
+    val takeWhile : ('T -> bool) -> 'T list -> 'T list
     val toArray : 'T list -> 'T[]
     val sortWith : ('T -> 'T -> int) -> 'T list -> 'T list