diff --git a/tests/string_test.cpp b/tests/string_test.cpp
index 472aacb..71998d8 100644
--- a/tests/string_test.cpp
+++ b/tests/string_test.cpp
@@ -17,8 +17,22 @@
 #include <gtest/gtest.h>
 
 #include <errno.h>
+#include <math.h>
 #include <string.h>
 
+#define KB 1024
+#define SMALL 1*KB
+#define LARGE 64*KB
+
+static int signum(int i) {
+  if (i < 0) {
+    return -1;
+  } else if (i > 0) {
+    return 1;
+  }
+  return 0;
+}
+
 TEST(string, strerror) {
   // Valid.
   ASSERT_STREQ("Success", strerror(0));
@@ -107,3 +121,544 @@
 
   ASSERT_STREQ("Unknown signal 1001", strsignal1001);
 }
+
+// TODO: where did these numbers come from?
+#define POS_ITER    10
+#define ITER        500
+
+// For every length we want to test, vary and change alignment
+// of allocated memory, fill it with some values, calculate
+// expected result and then run function and compare what we got.
+// These tests contributed by Intel Corporation.
+// TODO: make these tests more intention-revealing and less random.
+struct StringTestState {
+  StringTestState(size_t MAX_LEN) : MAX_LEN(MAX_LEN) {
+    int max_alignment = 64;
+
+    // TODO: fix the tests to not sometimes use twice their specified "MAX_LEN".
+    glob_ptr = reinterpret_cast<char*>(valloc(2 * MAX_LEN + max_alignment));
+    glob_ptr1 = reinterpret_cast<char*>(valloc(2 * MAX_LEN + max_alignment));
+    glob_ptr2 = reinterpret_cast<char*>(valloc(2 * MAX_LEN + max_alignment));
+
+    InitLenArray();
+
+    srandom(1234);
+  }
+
+  ~StringTestState() {
+    free(glob_ptr);
+    free(glob_ptr1);
+    free(glob_ptr2);
+  }
+
+  void NewIteration() {
+    int alignments[] = { 24, 32, 16, 48, 1, 2, 3, 0, 5, 11 };
+    int usable_alignments = 10;
+    int align1 = alignments[random() % (usable_alignments - 1)];
+    int align2 = alignments[random() % (usable_alignments - 1)];
+
+    ptr = glob_ptr + align1;
+    ptr1 = glob_ptr1 + align1;
+    ptr2 = glob_ptr2 + align2;
+  }
+
+  const size_t MAX_LEN;
+  char *ptr, *ptr1, *ptr2;
+  size_t n;
+  int len[ITER + 1];
+
+ private:
+  char *glob_ptr, *glob_ptr1, *glob_ptr2;
+
+  // Calculate input lengths and fill state.len with them.
+  // Test small lengths with more density than big ones. Manually push
+  // smallest (0) and biggest (MAX_LEN) lengths. Avoid repeats.
+  // Return number of lengths to test.
+  void InitLenArray() {
+    n = 0;
+    len[n++] = 0;
+    for (size_t i = 1; i < ITER; ++i) {
+      int l = (int) exp(log((double) MAX_LEN) * i / ITER);
+      if (l != len[n - 1]) {
+        len[n++] = l;
+      }
+    }
+    len[n++] = MAX_LEN;
+  }
+};
+
+TEST(string, strcat) {
+  StringTestState state(SMALL);
+  for (size_t i = 1; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr2, '\2', state.MAX_LEN);
+      state.ptr2[state.MAX_LEN - 1] = '\0';
+      memcpy(state.ptr, state.ptr2, 2 * state.MAX_LEN);
+
+      memset(state.ptr1, random() & 255, state.len[i]);
+      state.ptr1[random() % state.len[i]] = '\0';
+      state.ptr1[state.len[i] - 1] = '\0';
+
+      strcpy(state.ptr + state.MAX_LEN - 1, state.ptr1);
+
+      EXPECT_TRUE(strcat(state.ptr2, state.ptr1) == state.ptr2);
+      EXPECT_TRUE(memcmp(state.ptr, state.ptr2, 2 * state.MAX_LEN) == 0);
+    }
+  }
+}
+
+TEST(string, strchr) {
+  int seek_char = random() & 255;
+
+  StringTestState state(SMALL);
+  for (size_t i = 1; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      if (~seek_char > 0) {
+        memset(state.ptr1, ~seek_char, state.len[i]);
+      } else {
+        memset(state.ptr1, '\1', state.len[i]);
+      }
+      state.ptr1[state.len[i] - 1] = '\0';
+
+      int pos = random() % state.MAX_LEN;
+      char* expected;
+      if (pos >= state.len[i] - 1) {
+        if (seek_char == 0) {
+          expected = state.ptr1 + state.len[i] - 1;
+        } else {
+          expected = NULL;
+        }
+      } else {
+        state.ptr1[pos] = seek_char;
+        expected = state.ptr1 + pos;
+      }
+
+      ASSERT_TRUE(strchr(state.ptr1, seek_char) == expected);
+    }
+  }
+}
+
+TEST(string, strcmp) {
+  StringTestState state(SMALL);
+  for (size_t i = 1; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr1, 'v', state.MAX_LEN);
+      memset(state.ptr2, 'n', state.MAX_LEN);
+      state.ptr1[state.len[i] - 1] = '\0';
+      state.ptr2[state.len[i] - 1] = '\0';
+
+      int pos = 1 + (random() % (state.MAX_LEN - 1));
+      int actual;
+      int expected;
+      if (pos >= state.len[i] - 1) {
+        memcpy(state.ptr1, state.ptr2, state.len[i]);
+        expected = 0;
+        actual = strcmp(state.ptr1, state.ptr2);
+      } else {
+        memcpy(state.ptr1, state.ptr2, pos);
+        if (state.ptr1[pos] > state.ptr2[pos]) {
+          expected = 1;
+        } else if (state.ptr1[pos] == state.ptr2[pos]) {
+          state.ptr1[pos + 1] = '\0';
+          state.ptr2[pos + 1] = '\0';
+          expected = 0;
+        } else {
+          expected = -1;
+        }
+        actual = strcmp(state.ptr1, state.ptr2);
+      }
+
+      ASSERT_EQ(expected, signum(actual));
+    }
+  }
+}
+
+TEST(string, strcpy) {
+  StringTestState state(SMALL);
+  for (size_t j = 0; j < POS_ITER; j++) {
+    state.NewIteration();
+
+    size_t pos = random() % state.MAX_LEN;
+
+    memset(state.ptr1, '\2', pos);
+    state.ptr1[pos] = '\0';
+    state.ptr1[state.MAX_LEN - 1] = '\0';
+
+    memcpy(state.ptr, state.ptr1, state.MAX_LEN);
+
+    memset(state.ptr2, '\1', state.MAX_LEN);
+    state.ptr2[state.MAX_LEN - 1] = '\0';
+
+    memset(state.ptr + state.MAX_LEN, '\1', state.MAX_LEN);
+    memcpy(state.ptr + state.MAX_LEN, state.ptr1, pos + 1);
+    state.ptr[2 * state.MAX_LEN - 1] = '\0';
+
+    ASSERT_TRUE(strcpy(state.ptr2, state.ptr1) == state.ptr2);
+    ASSERT_FALSE((memcmp(state.ptr1, state.ptr, state.MAX_LEN)) != 0 ||
+                 (memcmp(state.ptr2, state.ptr + state.MAX_LEN, state.MAX_LEN) != 0));
+  }
+}
+
+#if __BIONIC__
+TEST(string, strlcat) {
+  StringTestState state(SMALL);
+  for (size_t i = 0; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr2, '\2', state.MAX_LEN + state.len[i]);
+      state.ptr2[state.MAX_LEN - 1] = '\0';
+      memcpy(state.ptr, state.ptr2, state.MAX_LEN + state.len[i]);
+
+      int pos = random() % state.MAX_LEN;
+      memset(state.ptr1, '\3', pos);
+      state.ptr1[pos] = '\0';
+      if (pos < state.len[i]) {
+        memcpy(state.ptr + state.MAX_LEN - 1, state.ptr1, pos + 1);
+      } else {
+        memcpy(state.ptr + state.MAX_LEN - 1, state.ptr1, state.len[i]);
+        state.ptr[state.MAX_LEN + state.len[i] - 1] = '\0';
+      }
+
+      strlcat(state.ptr2, state.ptr1, state.MAX_LEN + state.len[i]);
+
+      ASSERT_TRUE(memcmp(state.ptr, state.ptr2, state.MAX_LEN + state.len[i]) == 0);
+    }
+  }
+}
+#endif
+
+#if __BIONIC__
+TEST(string, strlcpy) {
+  StringTestState state(SMALL);
+  for (size_t j = 0; j < POS_ITER; j++) {
+    state.NewIteration();
+
+    int rand = random() & 255;
+    if (rand < 1) {
+      rand = 1;
+    }
+    memset(state.ptr1, rand, state.MAX_LEN);
+
+    size_t pos = random() % state.MAX_LEN;
+    if (pos < state.MAX_LEN) {
+      state.ptr1[pos] = '\0';
+    }
+    memcpy(state.ptr, state.ptr1, state.MAX_LEN);
+
+    memset(state.ptr2, random() & 255, state.MAX_LEN);
+    memcpy(state.ptr + state.MAX_LEN, state.ptr2, state.MAX_LEN);
+
+    if (pos > state.MAX_LEN - 1) {
+      memcpy(state.ptr + state.MAX_LEN, state.ptr1, state.MAX_LEN);
+      state.ptr[2 * state.MAX_LEN - 1] = '\0';
+    } else {
+      memcpy(state.ptr + state.MAX_LEN, state.ptr1, pos + 1);
+    }
+
+    ASSERT_EQ(strlcpy(state.ptr2, state.ptr1, state.MAX_LEN), strlen(state.ptr1));
+    ASSERT_FALSE((memcmp(state.ptr1, state.ptr, state.MAX_LEN) != 0) ||
+                 (memcmp(state.ptr2, state.ptr + state.MAX_LEN, state.MAX_LEN) != 0));
+  }
+}
+#endif
+
+TEST(string, strncat) {
+  StringTestState state(SMALL);
+  for (size_t i = 1; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr2, '\2', state.MAX_LEN);
+      state.ptr2[state.MAX_LEN - 1] = '\0';
+      memcpy(state.ptr, state.ptr2, 2 * state.MAX_LEN);
+
+      memset(state.ptr1, random() & 255, state.len[i]);
+      state.ptr1[random() % state.len[i]] = '\0';
+      state.ptr1[state.len[i] - 1] = '\0';
+
+      size_t pos = strlen(state.ptr1);
+
+      size_t actual = random() % state.len[i];
+      strncpy(state.ptr + state.MAX_LEN - 1, state.ptr1, std::min(actual, pos));
+      state.ptr[state.MAX_LEN + std::min(actual, pos) - 1] = '\0';
+
+      ASSERT_TRUE(strncat(state.ptr2, state.ptr1, actual) == state.ptr2);
+      ASSERT_EQ(memcmp(state.ptr, state.ptr2, 2 * state.MAX_LEN), 0);
+    }
+  }
+}
+
+TEST(string, strncmp) {
+  StringTestState state(SMALL);
+  for (size_t i = 1; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr1, 'v', state.MAX_LEN);
+      memset(state.ptr2, 'n', state.MAX_LEN);
+      state.ptr1[state.len[i] - 1] = '\0';
+      state.ptr2[state.len[i] - 1] = '\0';
+
+      int pos = 1 + (random() % (state.MAX_LEN - 1));
+      int actual;
+      int expected;
+      if (pos >= state.len[i] - 1) {
+        memcpy(state.ptr1, state.ptr2, state.len[i]);
+        expected = 0;
+        actual = strncmp(state.ptr1, state.ptr2, state.len[i]);
+      } else {
+        memcpy(state.ptr1, state.ptr2, pos);
+        if (state.ptr1[pos] > state.ptr2[pos]) {
+          expected = 1;
+        } else if (state.ptr1[pos] == state.ptr2[pos]) {
+          state.ptr1[pos + 1] = '\0';
+          state.ptr2[pos + 1] = '\0';
+          expected = 0;
+        } else {
+          expected = -1;
+        }
+        actual = strncmp(state.ptr1, state.ptr2, state.len[i]);
+      }
+
+      ASSERT_EQ(expected, signum(actual));
+    }
+  }
+}
+
+TEST(string, strncpy) {
+  StringTestState state(SMALL);
+  for (size_t j = 0; j < ITER; j++) {
+    state.NewIteration();
+
+    memset(state.ptr1, random() & 255, state.MAX_LEN);
+    state.ptr1[random () % state.MAX_LEN] = '\0';
+    memcpy(state.ptr, state.ptr1, state.MAX_LEN);
+
+    memset(state.ptr2, '\1', state.MAX_LEN);
+
+    size_t pos;
+    if (memchr(state.ptr1, 0, state.MAX_LEN)) {
+      pos = strlen(state.ptr1);
+    } else {
+      pos = state.MAX_LEN - 1;
+    }
+
+    memset(state.ptr + state.MAX_LEN, '\0', state.MAX_LEN);
+    memcpy(state.ptr + state.MAX_LEN, state.ptr1, pos + 1);
+
+    ASSERT_TRUE(strncpy(state.ptr2, state.ptr1, state.MAX_LEN) == state.ptr2);
+    ASSERT_FALSE(memcmp(state.ptr1, state.ptr, state.MAX_LEN) != 0 ||
+                 memcmp(state.ptr2, state.ptr + state.MAX_LEN, state.MAX_LEN) != 0);
+  }
+}
+
+TEST(string, strrchr) {
+  int seek_char = random() & 255;
+  StringTestState state(SMALL);
+  for (size_t i = 1; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      if (~seek_char > 0) {
+        memset(state.ptr1, ~seek_char, state.len[i]);
+      } else {
+        memset(state.ptr1, '\1', state.len[i]);
+      }
+      state.ptr1[state.len[i] - 1] = '\0';
+
+      int pos = random() % state.MAX_LEN;
+      char* expected;
+      if (pos >= state.len[i] - 1) {
+        if (seek_char == 0) {
+          expected = state.ptr1 + state.len[i] - 1;
+        } else {
+          expected = NULL;
+        }
+      } else {
+        state.ptr1[pos] = seek_char;
+        expected = state.ptr1 + pos;
+      }
+
+      ASSERT_TRUE(strrchr(state.ptr1, seek_char) == expected);
+    }
+  }
+}
+
+TEST(string, memchr) {
+  int seek_char = random() & 255;
+  StringTestState state(SMALL);
+  for (size_t i = 0; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr1, ~seek_char, state.len[i]);
+
+      int pos = random() % state.MAX_LEN;
+      char* expected;
+      if (pos >= state.len[i]) {
+        expected = NULL;
+      } else {
+        state.ptr1[pos] = seek_char;
+        expected = state.ptr1 + pos;
+      }
+
+      ASSERT_TRUE(memchr(state.ptr1, seek_char, state.len[i]) == expected);
+    }
+  }
+}
+
+TEST(string, memrchr) {
+  int seek_char = random() & 255;
+  StringTestState state(SMALL);
+  for (size_t i = 0; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr1, ~seek_char, state.len[i]);
+
+      int pos = random() % state.MAX_LEN;
+      char* expected;
+      if (pos >= state.len[i]) {
+        expected = NULL;
+      } else {
+        state.ptr1[pos] = seek_char;
+        expected = state.ptr1 + pos;
+      }
+
+      ASSERT_TRUE(memrchr(state.ptr1, seek_char, state.len[i]) == expected);
+    }
+  }
+}
+
+TEST(string, memcmp) {
+  StringTestState state(SMALL);
+  for (size_t i = 0; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      int c1 = random() & 0xff;
+      int c2 = random() & 0xff;
+      memset(state.ptr1, c1, state.MAX_LEN);
+      memset(state.ptr2, c1, state.MAX_LEN);
+
+      int pos = (state.len[i] == 0) ? 0 : (random() % state.len[i]);
+      state.ptr2[pos] = c2;
+
+      int expected = (static_cast<int>(c1) - static_cast<int>(c2));
+      int actual = memcmp(state.ptr1, state.ptr2, state.MAX_LEN);
+
+      ASSERT_EQ(signum(expected), signum(actual));
+    }
+  }
+}
+
+TEST(string, memcpy) {
+  StringTestState state(LARGE);
+  int rand = random() & 255;
+  for (size_t i = 0; i < state.n - 1; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      size_t pos = random() % (state.MAX_LEN - state.len[i]);
+
+      memset(state.ptr1, rand, state.len[i]);
+      memset(state.ptr1 + state.len[i], ~rand, state.MAX_LEN - state.len[i]);
+
+      memset(state.ptr2, rand, state.len[i]);
+      memset(state.ptr2 + state.len[i], ~rand, state.MAX_LEN - state.len[i]);
+      memset(state.ptr2 + pos, '\0', state.len[i]);
+
+      ASSERT_FALSE(memcpy(state.ptr2 + pos, state.ptr1 + pos, state.len[i]) != state.ptr2 + pos);
+      ASSERT_EQ(0, memcmp(state.ptr1, state.ptr2, state.MAX_LEN));
+    }
+  }
+}
+
+TEST(string, memset) {
+  StringTestState state(LARGE);
+  char ch = random () & 255;
+  for (size_t i = 0; i < state.n - 1; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr1, ~ch, state.MAX_LEN);
+      memcpy(state.ptr2, state.ptr1, state.MAX_LEN);
+
+      size_t pos = random () % (state.MAX_LEN - state.len[i]);
+      for (size_t k = pos; k < pos + state.len[i]; k++) {
+        state.ptr1[k] = ch;
+      }
+
+      ASSERT_TRUE(memset(state.ptr2 + pos, ch, state.len[i]) == state.ptr2 + pos);
+
+      ASSERT_EQ(0, memcmp(state.ptr1, state.ptr2, state.MAX_LEN));
+    }
+  }
+}
+
+TEST(string, memmove) {
+  StringTestState state(LARGE);
+  for (size_t i = 0; i < state.n - 1; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr1, random() & 255, 2 * state.MAX_LEN);
+
+      size_t pos = random() % (state.MAX_LEN - state.len[i]);
+
+      memset(state.ptr1, random() & 255, state.len[i]);
+      memcpy(state.ptr2, state.ptr1, 2 * state.MAX_LEN);
+      memcpy(state.ptr, state.ptr1, state.len[i]);
+      memcpy(state.ptr1 + pos, state.ptr, state.len[i]);
+
+      ASSERT_TRUE(memmove(state.ptr2 + pos, state.ptr2, state.len[i]) == state.ptr2 + pos);
+      ASSERT_EQ(0, memcmp(state.ptr2, state.ptr1, 2 * state.MAX_LEN));
+    }
+  }
+}
+
+TEST(string, bcopy) {
+  StringTestState state(LARGE);
+  for (size_t i = 0; i < state.n; i++) {
+    for (size_t j = 0; j < POS_ITER; j++) {
+      state.NewIteration();
+
+      memset(state.ptr1, random() & 255, state.MAX_LEN);
+      memset(state.ptr1 + state.MAX_LEN, random() & 255, state.MAX_LEN);
+      memcpy(state.ptr2, state.ptr1, 2 * state.MAX_LEN);
+
+      size_t start = random() % (2 * state.MAX_LEN - state.len[i]);
+      memcpy(state.ptr2 + start, state.ptr1, state.len[i]);
+
+      bcopy(state.ptr1, state.ptr1 + start, state.len[i]);
+      ASSERT_EQ(0, memcmp(state.ptr1, state.ptr2, 2 * state.MAX_LEN));
+    }
+  }
+}
+
+TEST(string, bzero) {
+  StringTestState state(LARGE);
+  for (size_t j = 0; j < ITER; j++) {
+    state.NewIteration();
+
+    memset(state.ptr1, random() & 255, state.MAX_LEN);
+
+    size_t start = random() % state.MAX_LEN;
+    size_t end = start + random() % (state.MAX_LEN - start);
+
+    memcpy(state.ptr2, state.ptr1, start);
+    memset(state.ptr2 + start, '\0', end - start);
+    memcpy(state.ptr2 + end, state.ptr1 + end, state.MAX_LEN - end);
+
+    bzero(state.ptr1 + start, end - start);
+
+    ASSERT_EQ(0, memcmp(state.ptr1, state.ptr2, state.MAX_LEN));
+  }
+}