diff --git a/std/algorithm.d b/std/algorithm.d
index 5841945e3..5c5aa72c2 100644
--- a/std/algorithm.d
+++ b/std/algorithm.d
@@ -3655,6 +3655,51 @@ unittest
     assert(countUntil!"a > b"([0, 7, 12, 22, 9], 20) == 3);
 }
 
+/++
+    Returns the number of elements which must be popped from $(D haystack)
+    before $(D pred(hastack.front)) is $(D true.).
+
+    Examples:
+--------------------
+assert(countUntil!(std.uni.isWhite)("hello world") == 5);
+assert(countUntil!(std.ascii.isDigit)("hello world") == -1);
+assert(countUntil!"a > 20"([0, 7, 12, 22, 9]) == 3);
+--------------------
+  +/
+sizediff_t countUntil(alias pred, R)(R haystack)
+if (isForwardRange!R && is(typeof(unaryFun!pred(haystack.front)) == bool))
+{
+    static if (isNarrowString!R)
+    {
+        // Narrow strings are handled a bit differently
+        auto length = haystack.length;
+        for (; !haystack.empty; haystack.popFront())
+        {
+            if (unaryFun!pred(haystack.front))
+            {
+                return length - haystack.length;
+            }
+        }
+    }
+    else
+    {
+        typeof(return) result;
+        for (; !haystack.empty; ++result, haystack.popFront())
+        {
+            if (unaryFun!pred(haystack.front)) return result;
+        }
+    }
+    return -1;
+}
+
+//Verify Examples.
+unittest
+{
+    assert(countUntil!(std.uni.isWhite)("hello world") == 5);
+    assert(countUntil!(std.ascii.isDigit)("hello world") == -1);
+    assert(countUntil!"a > 20"([0, 7, 12, 22, 9]) == 3);
+}
+
 /**
  * Same as $(D countUntil). This symbol has been scheduled for
  * deprecation because it is easily confused with the homonym function