diff --git a/CMakeLists.txt b/CMakeLists.txt
index 79f43ff..523ee83 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -99,6 +99,9 @@ set(SOURCES
   src/libc/stdio/printf.c
   # stdlib
   src/libc/stdlib/abs.c
+  src/libc/stdlib/atoi.c
+  src/libc/stdlib/atol.c
+  src/libc/stdlib/atoll.c
   src/libc/stdlib/calloc.c
   src/libc/stdlib/div.c
   src/libc/stdlib/labs.c
diff --git a/STATUS b/STATUS
index a7f1d24..3238b46 100644
--- a/STATUS
+++ b/STATUS
@@ -98,7 +98,7 @@ DONE:       Function/symbol/macro is defined, builds, links, and is tested
 
 7.20 <stdlib.h>
      7.20.1.1  atof: TODO
-     7.20.1.2  atoi, atol, atoll: TODO
+     7.20.1.2  atoi, atol, atoll: DONE
      7.20.1.3  strtod, strtof, strtold: TODO
      7.20.1.4  strtol, strtoul, strtoll, strtoull: DONE
      7.20.2  Pseudo-random sequence generation functions: TODO
diff --git a/include/stdlib.h b/include/stdlib.h
index db5cc60..63e8d91 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -63,6 +63,17 @@ div_t div(int __num, int __denom);
 ldiv_t ldiv(long int __num, long int __denom);
 lldiv_t lldiv(long long int __num, long long int __denom);
 
+/* Simplified numeric conversion functions. */
+
+/* ASCII to int. */
+extern int atoi(char const *__ptr);
+
+/* ASCII to long int. */
+extern long int atol(char const *__ptr);
+
+/* ASCII to long long int. */
+extern long long int atoll(char const *__ptr);
+
 /* Numeric conversion functions. */
 
 /* Parse a long int from a string. */
diff --git a/src/libc/stdlib/atoi.c b/src/libc/stdlib/atoi.c
new file mode 100644
index 0000000..1fe38c8
--- /dev/null
+++ b/src/libc/stdlib/atoi.c
@@ -0,0 +1,6 @@
+#include <stdlib.h>
+
+int atoi(char const *ptr)
+{
+	return (int)strtol(ptr, NULL, 10);
+}
diff --git a/src/libc/stdlib/atol.c b/src/libc/stdlib/atol.c
new file mode 100644
index 0000000..6195e5a
--- /dev/null
+++ b/src/libc/stdlib/atol.c
@@ -0,0 +1,6 @@
+#include <stdlib.h>
+
+long int atol(char const *ptr)
+{
+	return strtol(ptr, NULL, 10);
+}
diff --git a/src/libc/stdlib/atoll.c b/src/libc/stdlib/atoll.c
new file mode 100644
index 0000000..54816e3
--- /dev/null
+++ b/src/libc/stdlib/atoll.c
@@ -0,0 +1,6 @@
+#include <stdlib.h>
+
+long long int atoll(char const *ptr)
+{
+	return strtoll(ptr, NULL, 10);
+}