diff --git a/Tests/LibC/TestStrftime.cpp b/Tests/LibC/TestStrftime.cpp
index 7c0143c921c..fc70f374191 100644
--- a/Tests/LibC/TestStrftime.cpp
+++ b/Tests/LibC/TestStrftime.cpp
@@ -35,6 +35,9 @@ TEST_CASE(strftime)
     EXPECT(strftime(str, sizeof str, "The full name of the month is %B.", &t));
     EXPECT_EQ("The full name of the month is October."sv, str);
 
+    EXPECT(strftime(str, sizeof str, "The date and time is %c.", &t));
+    EXPECT_EQ("The date and time is Wed Oct 10 11:53:07 2018."sv, str);
+
     EXPECT(strftime(str, sizeof str, "The century is %C.", &t));
     EXPECT_EQ("The century is 20."sv, str);
 
@@ -47,6 +50,15 @@ TEST_CASE(strftime)
     EXPECT(strftime(str, sizeof str, "The day of the month is %e.", &t));
     EXPECT_EQ("The day of the month is 10."sv, str);
 
+    EXPECT(strftime(str, sizeof str, "The date is %F.", &t));
+    EXPECT_EQ("The date is 2018-10-10."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The two last digits of the week based year is %g.", &t));
+    EXPECT_EQ("The two last digits of the week based year is 18."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The week based year is %G.", &t));
+    EXPECT_EQ("The week based year is 2018."sv, str);
+
     EXPECT(strftime(str, sizeof str, "The short name of the month is %h.", &t));
     EXPECT_EQ("The short name of the month is Oct."sv, str);
 
@@ -101,6 +113,12 @@ TEST_CASE(strftime)
     EXPECT(strftime(str, sizeof str, "The week of the year is %W.", &t));
     EXPECT_EQ("The week of the year is 41."sv, str);
 
+    EXPECT(strftime(str, sizeof str, "The locale's appropriate date representation is %x.", &t));
+    EXPECT_EQ("The locale's appropriate date representation is 10/10/18."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The locale's appropriate time representation is %X.", &t));
+    EXPECT_EQ("The locale's appropriate time representation is 11:53:07."sv, str);
+
     EXPECT(strftime(str, sizeof str, "The year is %y.", &t));
     EXPECT_EQ("The year is 18."sv, str);
 
@@ -122,6 +140,9 @@ TEST_CASE(strftime_with_modifiers)
     t.tm_yday = 282;
     t.tm_isdst = -1;
 
+    EXPECT(strftime(str, sizeof str, "The date and time in the alternate representation is %Ec.", &t));
+    EXPECT_EQ("The date and time in the alternate representation is Wed Oct 10 11:53:07 2018."sv, str);
+
     EXPECT(strftime(str, sizeof str, "The century in the alternate representation is %EC.", &t));
     EXPECT_EQ("The century in the alternate representation is 20."sv, str);
 
diff --git a/Userland/Libraries/LibC/time.cpp b/Userland/Libraries/LibC/time.cpp
index 6db17f80a12..36e6b36ed4b 100644
--- a/Userland/Libraries/LibC/time.cpp
+++ b/Userland/Libraries/LibC/time.cpp
@@ -302,6 +302,16 @@ size_t strftime(char* destination, size_t max_size, char const* format, const st
             case 'B':
                 builder.append(long_month_names[tm->tm_mon]);
                 break;
+            case 'c':
+                builder.appendff("{} {} {:2} {:02}:{:02}:{:02} {}",
+                    short_day_names[tm->tm_wday],
+                    short_month_names[tm->tm_mon],
+                    tm->tm_mday,
+                    tm->tm_hour,
+                    tm->tm_min,
+                    tm->tm_sec,
+                    tm->tm_year + 1900);
+                break;
             case 'C':
                 builder.appendff("{:02}", (tm->tm_year + 1900) / 100);
                 break;
@@ -319,6 +329,17 @@ size_t strftime(char* destination, size_t max_size, char const* format, const st
                     return 0;
                 has_e_modifier = true;
                 goto continue_reading_operator;
+            case 'F':
+                builder.appendff("{}-{:02}-{:02}", tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday);
+                break;
+            case 'G':
+                dbgln("FIXME: Compute the week-based year instead of using the normal year.");
+                builder.appendff("{}", tm->tm_year + 1900);
+                break;
+            case 'g':
+                dbgln("FIXME: Compute the week-based year instead of using the normal year.");
+                builder.appendff("{:02}", (tm->tm_year + 1900) % 100);
+                break;
             case 'h':
                 builder.append(short_month_names[tm->tm_mon]);
                 break;
@@ -410,6 +431,12 @@ size_t strftime(char* destination, size_t max_size, char const* format, const st
                 builder.appendff("{:02}", week_number);
                 break;
             }
+            case 'x':
+                builder.appendff("{:02}/{:02}/{:02}", tm->tm_mon + 1, tm->tm_mday, (tm->tm_year + 1900) % 100);
+                break;
+            case 'X':
+                builder.appendff("{:02}:{:02}:{:02}", tm->tm_hour, tm->tm_min, tm->tm_sec);
+                break;
             case 'y':
                 builder.appendff("{:02}", (tm->tm_year + 1900) % 100);
                 break;