diff --git a/libc/include/llvm-libc-macros/netinet-in-macros.h b/libc/include/llvm-libc-macros/netinet-in-macros.h
index b04d6aa4b6781..88ffe92756b16 100644
--- a/libc/include/llvm-libc-macros/netinet-in-macros.h
+++ b/libc/include/llvm-libc-macros/netinet-in-macros.h
@@ -38,6 +38,24 @@
 // int and takes a single argument of type const struct in6_addr *:
 // https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/netinet_in.h.html
 
+#define IN6_IS_ADDR_UNSPECIFIED(a)                                             \
+  ((__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[0]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[1]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[2]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[3]) == 0)
+
+#define IN6_IS_ADDR_LOOPBACK(a)                                                \
+  ((__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[0]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[1]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[2]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[12]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[13]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[14]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[15]) == 1)
+
+#define IN6_IS_ADDR_MULTICAST(a)                                               \
+  (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[0]) == 0xff
+
 #define IN6_IS_ADDR_LINKLOCAL(a)                                               \
   ((__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[0]) == 0xfe &&            \
    (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xc0) == 0x80)
@@ -46,4 +64,24 @@
   ((__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[0]) == 0xfe &&            \
    (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xc0) == 0xc0)
 
+#define IN6_IS_ADDR_MC_NODELOCAL(a)                                            \
+  (IN6_IS_ADDR_MULTICAST(a) &&                                                 \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xf) == 0x1)
+
+#define IN6_IS_ADDR_MC_LINKLOCAL(a)                                            \
+  (IN6_IS_ADDR_MULTICAST(a) &&                                                 \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xf) == 0x2)
+
+#define IN6_IS_ADDR_MC_SITELOCAL(a)                                            \
+  (IN6_IS_ADDR_MULTICAST(a) &&                                                 \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xf) == 0x5)
+
+#define IN6_IS_ADDR_MC_ORGLOCAL(a)                                             \
+  (IN6_IS_ADDR_MULTICAST(a) &&                                                 \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xf) == 0x8)
+
+#define IN6_IS_ADDR_MC_GLOBAL(a)                                               \
+  (IN6_IS_ADDR_MULTICAST(a) &&                                                 \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xf) == 0xe)
+
 #endif // LLVM_LIBC_MACROS_NETINET_IN_MACROS_H
diff --git a/libc/test/include/netinet_in_test.cpp b/libc/test/include/netinet_in_test.cpp
index 6937262f92e90..72500c4d51438 100644
--- a/libc/test/include/netinet_in_test.cpp
+++ b/libc/test/include/netinet_in_test.cpp
@@ -12,6 +12,23 @@
 TEST(LlvmLibcNetinetInTest, IN6Macro) {
   char buff[16] = {};
 
+  EXPECT_TRUE(IN6_IS_ADDR_UNSPECIFIED(buff));
+  for (int i = 0; i < 16; ++i) {
+    buff[i] = 1;
+    EXPECT_FALSE(IN6_IS_ADDR_UNSPECIFIED(buff));
+    buff[i] = 0;
+  }
+
+  EXPECT_FALSE(IN6_IS_ADDR_LOOPBACK(buff));
+  buff[15] = 1;
+  EXPECT_TRUE(IN6_IS_ADDR_LOOPBACK(buff));
+  buff[15] = 0;
+
+  EXPECT_FALSE(IN6_IS_ADDR_MULTICAST(buff));
+  buff[0] = 0xff;
+  EXPECT_TRUE(IN6_IS_ADDR_MULTICAST(buff));
+  buff[0] = 0;
+
   buff[0] = 0xfe;
   buff[1] = 0x80;
   EXPECT_TRUE(IN6_IS_ADDR_LINKLOCAL(buff));
@@ -25,4 +42,18 @@ TEST(LlvmLibcNetinetInTest, IN6Macro) {
   buff[0] = 0xff;
   buff[1] = 0x80;
   EXPECT_FALSE(IN6_IS_ADDR_SITELOCAL(buff));
+
+  buff[0] = 0xff;
+  buff[1] = 0x1;
+  EXPECT_TRUE(IN6_IS_ADDR_MC_NODELOCAL(buff));
+  buff[1] = 0x2;
+  EXPECT_TRUE(IN6_IS_ADDR_MC_LINKLOCAL(buff));
+  buff[1] = 0x5;
+  EXPECT_TRUE(IN6_IS_ADDR_MC_SITELOCAL(buff));
+  buff[1] = 0x8;
+  EXPECT_TRUE(IN6_IS_ADDR_MC_ORGLOCAL(buff));
+  buff[1] = 0xe;
+  EXPECT_TRUE(IN6_IS_ADDR_MC_GLOBAL(buff));
+  buff[1] = 0;
+  buff[0] = 0;
 }