diff --git a/common/lib/mem.asm_x86_64 b/common/lib/mem.asm_x86_64
new file mode 100644
index 00000000..4463c197
--- /dev/null
+++ b/common/lib/mem.asm_x86_64
@@ -0,0 +1,55 @@
+section .text
+
+global memcpy
+memcpy:
+    mov rcx, rdx
+    mov rax, rdi
+    rep movsb
+    ret
+
+global memset
+memset:
+    push rdi
+    mov rax, rsi
+    mov rcx, rdx
+    rep stosb
+    pop rax
+    ret
+
+global memmove
+memmove:
+    mov rcx, rdx
+    mov rax, rdi
+
+    cmp rdi, rsi
+    ja .copy_backwards
+
+    rep movsb
+    jmp .done
+
+  .copy_backwards:
+    lea rdi, [rdi+rcx-1]
+    lea rsi, [rsi+rcx-1]
+    std
+    rep movsb
+    cld
+
+  .done:
+    ret
+
+global memcmp
+memcmp:
+    mov rcx, rdx
+    repe cmpsb
+    je .equal
+
+    mov al, byte [rdi-1]
+    sub al, byte [rsi-1]
+    movsx rax, al
+    jmp .done
+
+  .equal:
+    xor eax, eax
+
+  .done:
+    ret
diff --git a/common/lib/mem.s2.asm_ia32 b/common/lib/mem.s2.asm_ia32
index dc0b8d92..c4452247 100644
--- a/common/lib/mem.s2.asm_ia32
+++ b/common/lib/mem.s2.asm_ia32
@@ -1,5 +1,79 @@
 section .text
 
+global memcpy
+memcpy:
+    push esi
+    push edi
+    mov eax, dword [esp+12]
+    mov edi, eax
+    mov esi, dword [esp+16]
+    mov ecx, dword [esp+20]
+    rep movsb
+    pop edi
+    pop esi
+    ret
+
+global memset
+memset:
+    push edi
+    mov edx, dword [esp+8]
+    mov edi, edx
+    mov eax, dword [esp+12]
+    mov ecx, dword [esp+16]
+    rep stosb
+    mov eax, edx
+    pop edi
+    ret
+
+global memmove
+memmove:
+    push esi
+    push edi
+    mov eax, dword [esp+12]
+    mov edi, eax
+    mov esi, dword [esp+16]
+    mov ecx, dword [esp+20]
+
+    cmp edi, esi
+    ja .copy_backwards
+
+    rep movsb
+    jmp .done
+
+  .copy_backwards:
+    lea edi, [edi+ecx-1]
+    lea esi, [esi+ecx-1]
+    std
+    rep movsb
+    cld
+
+  .done:
+    pop edi
+    pop esi
+    ret
+
+global memcmp
+memcmp:
+    push esi
+    push edi
+    mov edi, dword [esp+12]
+    mov esi, dword [esp+16]
+    mov ecx, dword [esp+20]
+    repe cmpsb
+    je .equal
+    mov al, byte [edi-1]
+    sub al, byte [esi-1]
+    movsx eax, al
+    jmp .done
+
+  .equal:
+    xor eax, eax
+
+  .done:
+    pop edi
+    pop esi
+    ret
+
 global memcpy32to64
 memcpy32to64:
     push ebp
diff --git a/common/lib/memory.s2.c b/common/lib/memory.s2.c
index 6d530115..0c3b7edd 100644
--- a/common/lib/memory.s2.c
+++ b/common/lib/memory.s2.c
@@ -1,3 +1,5 @@
+#if !defined (__x86_64__) && !defined (__i386__)
+
 #include <stdint.h>
 #include <stddef.h>
 
@@ -51,3 +53,5 @@ int memcmp(const void *s1, const void *s2, size_t n) {
 
     return 0;
 }
+
+#endif
diff --git a/decompressor/mem.asm b/decompressor/mem.asm
new file mode 100644
index 00000000..d3a7d9e7
--- /dev/null
+++ b/decompressor/mem.asm
@@ -0,0 +1,75 @@
+section .text
+
+global memcpy
+memcpy:
+    push esi
+    push edi
+    mov eax, dword [esp+12]
+    mov edi, eax
+    mov esi, dword [esp+16]
+    mov ecx, dword [esp+20]
+    rep movsb
+    pop edi
+    pop esi
+    ret
+
+global memset
+memset:
+    push edi
+    mov edx, dword [esp+8]
+    mov edi, edx
+    mov eax, dword [esp+12]
+    mov ecx, dword [esp+16]
+    rep stosb
+    mov eax, edx
+    pop edi
+    ret
+
+global memmove
+memmove:
+    push esi
+    push edi
+    mov eax, dword [esp+12]
+    mov edi, eax
+    mov esi, dword [esp+16]
+    mov ecx, dword [esp+20]
+
+    cmp edi, esi
+    ja .copy_backwards
+
+    rep movsb
+    jmp .done
+
+  .copy_backwards:
+    lea edi, [edi+ecx-1]
+    lea esi, [esi+ecx-1]
+    std
+    rep movsb
+    cld
+
+  .done:
+    pop edi
+    pop esi
+    ret
+
+global memcmp
+memcmp:
+    push esi
+    push edi
+    mov edi, dword [esp+12]
+    mov esi, dword [esp+16]
+    mov ecx, dword [esp+20]
+    repe cmpsb
+    je .equal
+    mov al, byte [edi-1]
+    sub al, byte [esi-1]
+    movsx eax, al
+    jmp .done
+
+  .equal:
+    xor eax, eax
+
+  .done:
+    pop edi
+    pop esi
+    ret
diff --git a/decompressor/memory.c b/decompressor/memory.c
deleted file mode 100644
index 6d530115..00000000
--- a/decompressor/memory.c
+++ /dev/null
@@ -1,53 +0,0 @@
-#include <stdint.h>
-#include <stddef.h>
-
-void *memcpy(void *dest, const void *src, size_t n) {
-    uint8_t *pdest = (uint8_t *)dest;
-    const uint8_t *psrc = (const uint8_t *)src;
-
-    for (size_t i = 0; i < n; i++) {
-        pdest[i] = psrc[i];
-    }
-
-    return dest;
-}
-
-void *memset(void *s, int c, size_t n) {
-    uint8_t *p = (uint8_t *)s;
-
-    for (size_t i = 0; i < n; i++) {
-        p[i] = (uint8_t)c;
-    }
-
-    return s;
-}
-
-void *memmove(void *dest, const void *src, size_t n) {
-    uint8_t *pdest = (uint8_t *)dest;
-    const uint8_t *psrc = (const uint8_t *)src;
-
-    if (src > dest) {
-        for (size_t i = 0; i < n; i++) {
-            pdest[i] = psrc[i];
-        }
-    } else if (src < dest) {
-        for (size_t i = n; i > 0; i--) {
-            pdest[i-1] = psrc[i-1];
-        }
-    }
-
-    return dest;
-}
-
-int memcmp(const void *s1, const void *s2, size_t n) {
-    const uint8_t *p1 = (const uint8_t *)s1;
-    const uint8_t *p2 = (const uint8_t *)s2;
-
-    for (size_t i = 0; i < n; i++) {
-        if (p1[i] != p2[i]) {
-            return p1[i] < p2[i] ? -1 : 1;
-        }
-    }
-
-    return 0;
-}