diff --git a/src/core/iomgr/alarm_heap.c b/src/core/iomgr/alarm_heap.c
new file mode 100644
index 0000000..693d26d
--- /dev/null
+++ b/src/core/iomgr/alarm_heap.c
@@ -0,0 +1,148 @@
+/*
+ *
+ * Copyright 2014, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/iomgr/alarm_heap.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/useful.h>
+
+/* Adjusts a heap so as to move a hole at position i closer to the root,
+   until a suitable position is found for element t. Then, copies t into that
+   position. This functor is called each time immediately after modifying a
+   value in the underlying container, with the offset of the modified element as
+   its argument. */
+static void adjust_upwards(grpc_alarm **first, int i, grpc_alarm *t) {
+  while (i > 0) {
+    int parent = (i - 1) / 2;
+    if (gpr_time_cmp(first[parent]->deadline, t->deadline) >= 0) break;
+    first[i] = first[parent];
+    first[i]->heap_index = i;
+    i = parent;
+  }
+  first[i] = t;
+  t->heap_index = i;
+}
+
+/* Adjusts a heap so as to move a hole at position i farther away from the root,
+   until a suitable position is found for element t.  Then, copies t into that
+   position. */
+static void adjust_downwards(grpc_alarm **first, int i, int length,
+                             grpc_alarm *t) {
+  for (;;) {
+    int left_child = 1 + 2 * i;
+    int right_child;
+    int next_i;
+    if (left_child >= length) break;
+    right_child = left_child + 1;
+    next_i = right_child < length &&
+                     gpr_time_cmp(first[left_child]->deadline,
+                                  first[right_child]->deadline) < 0
+                 ? right_child
+                 : left_child;
+    if (gpr_time_cmp(t->deadline, first[next_i]->deadline) >= 0) break;
+    first[i] = first[next_i];
+    first[i]->heap_index = i;
+    i = next_i;
+  }
+  first[i] = t;
+  t->heap_index = i;
+}
+
+#define SHRINK_MIN_ELEMS 8
+#define SHRINK_FULLNESS_FACTOR 2
+
+static void maybe_shrink(grpc_alarm_heap *heap) {
+  if (heap->alarm_count >= 8 &&
+      heap->alarm_count <= heap->alarm_capacity / SHRINK_FULLNESS_FACTOR / 2) {
+    heap->alarm_capacity = heap->alarm_count * SHRINK_FULLNESS_FACTOR;
+    heap->alarms =
+        gpr_realloc(heap->alarms, heap->alarm_capacity * sizeof(grpc_alarm *));
+  }
+}
+
+static void note_changed_priority(grpc_alarm_heap *heap, grpc_alarm *alarm) {
+  int i = alarm->heap_index;
+  int parent = (i - 1) / 2;
+  if (gpr_time_cmp(heap->alarms[parent]->deadline, alarm->deadline) < 0) {
+    adjust_upwards(heap->alarms, i, alarm);
+  } else {
+    adjust_downwards(heap->alarms, i, heap->alarm_count, alarm);
+  }
+}
+
+void grpc_alarm_heap_init(grpc_alarm_heap *heap) {
+  memset(heap, 0, sizeof(*heap));
+}
+
+void grpc_alarm_heap_destroy(grpc_alarm_heap *heap) { gpr_free(heap->alarms); }
+
+int grpc_alarm_heap_add(grpc_alarm_heap *heap, grpc_alarm *alarm) {
+  if (heap->alarm_count == heap->alarm_capacity) {
+    heap->alarm_capacity =
+        GPR_MAX(heap->alarm_capacity + 1, heap->alarm_capacity * 3 / 2);
+    heap->alarms =
+        gpr_realloc(heap->alarms, heap->alarm_capacity * sizeof(grpc_alarm *));
+  }
+  alarm->heap_index = heap->alarm_count;
+  adjust_upwards(heap->alarms, heap->alarm_count, alarm);
+  heap->alarm_count++;
+  return alarm->heap_index == 0;
+}
+
+void grpc_alarm_heap_remove(grpc_alarm_heap *heap, grpc_alarm *alarm) {
+  int i = alarm->heap_index;
+  if (i == heap->alarm_count - 1) {
+    heap->alarm_count--;
+    maybe_shrink(heap);
+    return;
+  }
+  heap->alarms[i] = heap->alarms[heap->alarm_count - 1];
+  heap->alarms[i]->heap_index = i;
+  heap->alarm_count--;
+  maybe_shrink(heap);
+  note_changed_priority(heap, heap->alarms[i]);
+}
+
+int grpc_alarm_heap_is_empty(grpc_alarm_heap *heap) {
+  return heap->alarm_count == 0;
+}
+
+grpc_alarm *grpc_alarm_heap_top(grpc_alarm_heap *heap) {
+  return heap->alarms[0];
+}
+
+void grpc_alarm_heap_pop(grpc_alarm_heap *heap) {
+  grpc_alarm_heap_remove(heap, grpc_alarm_heap_top(heap));
+}