Index: libc/src/__support/CPP/blockstore.h
===================================================================
--- libc/src/__support/CPP/blockstore.h
+++ libc/src/__support/CPP/blockstore.h
@@ -113,6 +113,29 @@
     *ptr = value;
   }
 
+  T &back() {
+    static_assert(REVERSE_ORDER);
+    return *begin();
+  }
+
+  void pop_back() {
+    static_assert(REVERSE_ORDER);
+    // TOOD should be calling "back().~T()" here but we don't run destructors
+    // in destrory either.
+    fill_count--;
+    if (fill_count || current == &first)
+      return;
+    Block *old = current;
+    current = current->next;
+    if (old != &first)
+      ::free(old);
+    fill_count = BLOCK_SIZE;
+  }
+
+  bool empty() const {
+    return current == &first && !fill_count;
+  }
+
   iterator begin() {
     if (REVERSE_ORDER)
       return iterator(current, fill_count);
Index: libc/test/src/__support/CPP/blockstore_test.cpp
===================================================================
--- libc/test/src/__support/CPP/blockstore_test.cpp
+++ libc/test/src/__support/CPP/blockstore_test.cpp
@@ -66,3 +66,24 @@
 TEST_F(LlvmLibcBlockStoreTest, PopulateAndIterateReverse10) {
   populate_and_iterate<4, 10, true>();
 }
+
+TEST_F(LlvmLibcBlockStoreTest, Back) {
+  using __llvm_libc::cpp::BlockStore;
+  BlockStore<int, 4, true> block_store;
+  for (int i = 0; i < 20; i++)
+    block_store.push_back(i);
+  for (int i = 19; i >= 0; i--, block_store.pop_back())
+    ASSERT_EQ(block_store.back(), i);
+  block_store.destroy(&block_store);
+}
+
+TEST_F(LlvmLibcBlockStoreTest, Empty) {
+  using __llvm_libc::cpp::BlockStore;
+  BlockStore<int, 2, true> block_store;
+
+  ASSERT_TRUE(block_store.empty());
+  block_store.push_back(1);
+  for (int i = 0; i < 10; i++, block_store.push_back(1))
+    ASSERT_FALSE(block_store.empty());
+  block_store.destroy(&block_store);
+}