diff --git a/libc/include/locale.h b/libc/include/locale.h
index e0740303..45493c6a 100644
--- a/libc/include/locale.h
+++ b/libc/include/locale.h
@@ -5,6 +5,28 @@
 
 #include <bits/locale-cat.h>
 
+struct lconv
+{
+    char* decimal_point;
+    char* thousands_sep;
+    char* grouping;
+    char* int_curr_symbol;
+    char* currency_symbol;
+    char* mon_decimal_point;
+    char* mon_thousands_sep;
+    char* mon_grouping;
+    char* positive_sign;
+    char* negative_sign;
+    char int_frac_digits;
+    char frac_digits;
+    char p_cs_precedes;
+    char p_sep_by_space;
+    char n_cs_precedes;
+    char n_sep_by_space;
+    char p_sign_posn;
+    char n_sign_posn;
+};
+
 #ifdef __cplusplus
 extern "C"
 {
@@ -13,6 +35,9 @@ extern "C"
     // Query or set the current locale.
     char* setlocale(int category, const char* locale);
 
+    // Query formatting information for the current locale.
+    struct lconv* localeconv(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/libc/include/string.h b/libc/include/string.h
index 800c3947..6b87f20e 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -98,6 +98,9 @@ extern "C"
     /* Compare two null-terminated strings according to the current locale. */
     int strcoll(const char* a, const char* b);
 
+    /* Transform a string according to the current locale. */
+    size_t strxfrm(char* dest, const char* src, size_t n);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/libc/include/time.h b/libc/include/time.h
index 8f4291aa..3e725293 100644
--- a/libc/include/time.h
+++ b/libc/include/time.h
@@ -7,6 +7,10 @@
 #include <bits/struct_tm.h>
 #include <bits/timespec.h>
 
+typedef long int clock_t;
+
+#define CLOCKS_PER_SEC 1000000
+
 #ifdef __cplusplus
 extern "C"
 {
@@ -42,9 +46,18 @@ extern "C"
     /* Build a string representation of UNIX time. */
     char* ctime_r(const time_t* tp, char buf[26]);
 
+    /* Convert broken-down time back into UNIX time. */
+    time_t mktime(struct tm* tm);
+
     /* Format a string representation of broken-down time using a format string. */
     size_t strftime(char* buf, size_t max, const char* format, const struct tm* tm);
 
+    /* Return the difference in seconds between two times. */
+    double difftime(time_t a, time_t b);
+
+    /* Estimate the CPU time used by a process. */
+    clock_t clock(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/libc/src/locale.cpp b/libc/src/locale.cpp
index 19c508ab..1db886a4 100644
--- a/libc/src/locale.cpp
+++ b/libc/src/locale.cpp
@@ -1,6 +1,30 @@
+#include <limits.h>
 #include <locale.h>
 
 static char s_default_locale[] = "C";
+static char s_empty_string[] = "";
+static char s_decimal_point[] = ".";
+
+static struct lconv s_lconv = {
+    .decimal_point = s_decimal_point,
+    .thousands_sep = s_empty_string,
+    .grouping = s_empty_string,
+    .int_curr_symbol = s_empty_string,
+    .currency_symbol = s_empty_string,
+    .mon_decimal_point = s_empty_string,
+    .mon_thousands_sep = s_empty_string,
+    .mon_grouping = s_empty_string,
+    .positive_sign = s_empty_string,
+    .negative_sign = s_empty_string,
+    .int_frac_digits = CHAR_MAX,
+    .frac_digits = CHAR_MAX,
+    .p_cs_precedes = CHAR_MAX,
+    .p_sep_by_space = CHAR_MAX,
+    .n_cs_precedes = CHAR_MAX,
+    .n_sep_by_space = CHAR_MAX,
+    .p_sign_posn = CHAR_MAX,
+    .n_sign_posn = CHAR_MAX,
+};
 
 extern "C"
 {
@@ -9,4 +33,9 @@ extern "C"
         // FIXME: Set the current locale if <locale> is not NULL.
         return s_default_locale;
     }
+
+    struct lconv* localeconv(void)
+    {
+        return &s_lconv;
+    }
 }
diff --git a/libc/src/string.cpp b/libc/src/string.cpp
index 7aa55706..026b1953 100644
--- a/libc/src/string.cpp
+++ b/libc/src/string.cpp
@@ -15,6 +15,12 @@ extern "C"
         return strcmp(a, b);
     }
 
+    size_t strxfrm(char* dest, const char* src, size_t n)
+    {
+        strncpy(dest, src, n);
+        return n;
+    }
+
     char* strerror(int errnum)
     {
         return const_cast<char*>(error_string(errnum));
diff --git a/libc/src/time.cpp b/libc/src/time.cpp
index 33c6a22e..7f13646a 100644
--- a/libc/src/time.cpp
+++ b/libc/src/time.cpp
@@ -3,6 +3,7 @@
 #include <luna/Format.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/resource.h>
 #include <sys/syscall.h>
 #include <time.h>
 #include <unistd.h>
@@ -31,6 +32,13 @@ static int day_of_week(int year, int mon, int day)
     return (year + year / 4 - year / 100 + year / 400 + t[mon - 1] + day) % 7;
 }
 
+// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_16
+static constexpr u64 broken_down_to_unix(u64 year, u64 yday, u64 hour, u64 min, u64 sec)
+{
+    return sec + min * 60 + hour * 3600 + yday * 86400 + (year - 70) * 31536000 + ((year - 69) / 4) * 86400 -
+           ((year - 1) / 100) * 86400 + ((year + 299) / 400) * 86400;
+}
+
 static void time_to_struct_tm(time_t time, struct tm* result)
 {
     result->tm_isdst = 0; // No DST/timezone support for now.
@@ -167,4 +175,29 @@ extern "C"
 
         return 0;
     }
+
+    time_t mktime(struct tm* tm)
+    {
+        // FIXME: Check if the tm structure is valid.
+        time_t result = broken_down_to_unix(tm->tm_year, make_yday(tm->tm_year, tm->tm_mon + 1) + (tm->tm_mday - 1),
+                                            tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+        tm->tm_yday = make_yday(tm->tm_year + 1900, tm->tm_mon + 1) + (tm->tm_mday - 1);
+        tm->tm_wday = day_of_week(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday);
+
+        return result;
+    }
+
+    double difftime(time_t a, time_t b)
+    {
+        return (double)(a - b);
+    }
+
+    clock_t clock(void)
+    {
+        struct rusage ru;
+        if (getrusage(RUSAGE_SELF, &ru) < 0) return (clock_t)-1;
+
+        return ru.ru_utime.tv_sec * CLOCKS_PER_SEC + ru.ru_utime.tv_usec;
+    }
 }