diff --git a/CMakeLists.txt b/CMakeLists.txt
index ba16732ff..484a1d4d7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -496,6 +496,8 @@ set(HLE_LIBC_INTERNAL_LIB src/core/libraries/libc_internal/libc_internal.cpp
                  src/core/libraries/libc_internal/libc_internal_str.h
                  src/core/libraries/libc_internal/libc_internal_math.cpp
                  src/core/libraries/libc_internal/libc_internal_math.h
+                 src/core/libraries/libc_internal/libc_internal_threads.cpp
+                 src/core/libraries/libc_internal/libc_internal_threads.h
                  src/core/libraries/libc_internal/printf.h
 )
 
diff --git a/src/core/libraries/kernel/file_system.h b/src/core/libraries/kernel/file_system.h
index 507f0952c..d8989828a 100644
--- a/src/core/libraries/kernel/file_system.h
+++ b/src/core/libraries/kernel/file_system.h
@@ -65,6 +65,9 @@ constexpr int ORBIS_KERNEL_O_DSYNC = 0x1000;
 constexpr int ORBIS_KERNEL_O_DIRECT = 0x00010000;
 constexpr int ORBIS_KERNEL_O_DIRECTORY = 0x00020000;
 
+s32 PS4_SYSV_ABI posix_open(const char* path, s32 flags, u16 mode);
+s32 PS4_SYSV_ABI posix_close(s32 fd);
+s64 PS4_SYSV_ABI posix_lseek(s32 fd, s64 offset, s32 whence);
 s64 PS4_SYSV_ABI sceKernelWrite(s32 fd, const void* buf, u64 nbytes);
 s64 PS4_SYSV_ABI sceKernelRead(s32 fd, void* buf, u64 nbytes);
 s64 PS4_SYSV_ABI sceKernelPread(s32 fd, void* buf, u64 nbytes, s64 offset);
diff --git a/src/core/libraries/kernel/threads.h b/src/core/libraries/kernel/threads.h
index bcccf1695..42ab0b13f 100644
--- a/src/core/libraries/kernel/threads.h
+++ b/src/core/libraries/kernel/threads.h
@@ -28,6 +28,16 @@ int PS4_SYSV_ABI posix_pthread_create(PthreadT* thread, const PthreadAttrT* attr
 
 int PS4_SYSV_ABI posix_pthread_join(PthreadT pthread, void** thread_return);
 
+int PS4_SYSV_ABI posix_pthread_mutexattr_init(PthreadMutexAttrT* attr);
+int PS4_SYSV_ABI posix_pthread_mutexattr_settype(PthreadMutexAttrT* attr, PthreadMutexType type);
+int PS4_SYSV_ABI posix_pthread_mutexattr_destroy(PthreadMutexAttrT* attr);
+
+int PS4_SYSV_ABI scePthreadMutexInit(PthreadMutexT* mutex, const PthreadMutexAttrT* mutex_attr,
+                                     const char* name);
+int PS4_SYSV_ABI posix_pthread_mutex_lock(PthreadMutexT* mutex);
+int PS4_SYSV_ABI posix_pthread_mutex_unlock(PthreadMutexT* mutex);
+int PS4_SYSV_ABI posix_pthread_mutex_destroy(PthreadMutexT* mutex);
+
 void RegisterThreads(Core::Loader::SymbolsResolver* sym);
 
 class Thread {
diff --git a/src/core/libraries/libc_internal/libc_internal.cpp b/src/core/libraries/libc_internal/libc_internal.cpp
index df35680a4..6a92d2317 100644
--- a/src/core/libraries/libc_internal/libc_internal.cpp
+++ b/src/core/libraries/libc_internal/libc_internal.cpp
@@ -11,6 +11,7 @@
 #include "libc_internal_math.h"
 #include "libc_internal_memory.h"
 #include "libc_internal_str.h"
+#include "libc_internal_threads.h"
 #include "printf.h"
 
 namespace Libraries::LibcInternal {
@@ -20,5 +21,11 @@ void RegisterLib(Core::Loader::SymbolsResolver* sym) {
     RegisterlibSceLibcInternalStr(sym);
     RegisterlibSceLibcInternalMemory(sym);
     RegisterlibSceLibcInternalIo(sym);
+    RegisterlibSceLibcInternalThreads(sym);
+}
+
+void ForceRegisterLib(Core::Loader::SymbolsResolver* sym) {
+    // Used to forcibly enable HLEs for broken LLE functions.
+    ForceRegisterlibSceLibcInternalIo(sym);
 }
 } // namespace Libraries::LibcInternal
\ No newline at end of file
diff --git a/src/core/libraries/libc_internal/libc_internal.h b/src/core/libraries/libc_internal/libc_internal.h
index 9b00b72d8..1494a2ab2 100644
--- a/src/core/libraries/libc_internal/libc_internal.h
+++ b/src/core/libraries/libc_internal/libc_internal.h
@@ -15,4 +15,5 @@ namespace Libraries::LibcInternal {
 // so everything is just in the .cpp file
 
 void RegisterLib(Core::Loader::SymbolsResolver* sym);
+void ForceRegisterLib(Core::Loader::SymbolsResolver* sym);
 } // namespace Libraries::LibcInternal
\ No newline at end of file
diff --git a/src/core/libraries/libc_internal/libc_internal_io.cpp b/src/core/libraries/libc_internal/libc_internal_io.cpp
index 8105b66cc..504ba5b48 100644
--- a/src/core/libraries/libc_internal/libc_internal_io.cpp
+++ b/src/core/libraries/libc_internal/libc_internal_io.cpp
@@ -3,21 +3,484 @@
 
 #include <cstdarg>
 #include <cstdio>
+#include <map>
 
 #include <common/va_ctx.h>
+#include "common/alignment.h"
 #include "common/assert.h"
 #include "common/logging/log.h"
 #include "core/libraries/error_codes.h"
+#include "core/libraries/kernel/file_system.h"
+#include "core/libraries/kernel/kernel.h"
+#include "core/libraries/kernel/posix_error.h"
+#include "core/libraries/libc_internal/libc_internal_io.h"
+#include "core/libraries/libc_internal/libc_internal_threads.h"
 #include "core/libraries/libs.h"
-#include "libc_internal_io.h"
 #include "printf.h"
 
 namespace Libraries::LibcInternal {
-int PS4_SYSV_ABI internal_snprintf(char* s, size_t n, VA_ARGS) {
+
+s32 PS4_SYSV_ABI internal_snprintf(char* s, u64 n, VA_ARGS) {
     VA_CTX(ctx);
     return snprintf_ctx(s, n, &ctx);
 }
+
+std::map<s32, OrbisFILE*> g_files{};
+// Constants for tracking accurate file indexes.
+// Since the file struct is exposed to the application, accuracy is important.
+static constexpr s32 g_initial_files = 5;
+static constexpr s32 g_max_files = 0x100;
+
+OrbisFILE* PS4_SYSV_ABI internal__Fofind() {
+    u64 index = g_initial_files;
+    while (index != g_max_files) {
+        OrbisFILE* file = g_files[index];
+        // If file doesn't exist, create it.
+        if (file == nullptr) {
+            file = new OrbisFILE();
+            if (file == nullptr) {
+                return nullptr;
+            }
+            // Store new file in the array, initialize default values, and return it.
+            g_files[index] = file;
+            file->_Mode = 0x80;
+            file->_Idx = index;
+            return file;
+        }
+        // Special case, files with mode 0 are returned?
+        if (file->_Mode == 0) {
+            file->_Mode = 0xff7f;
+            return file;
+        }
+        index++;
+    }
+    return nullptr;
+}
+
+void PS4_SYSV_ABI internal__Lockfilelock(OrbisFILE* file) {
+    if (file != nullptr && file->_Mutex != nullptr) {
+        internal__Mtxlock(&file->_Mutex);
+    }
+}
+
+void PS4_SYSV_ABI internal__Unlockfilelock(OrbisFILE* file) {
+    if (file != nullptr && file->_Mutex != nullptr) {
+        internal__Mtxunlock(&file->_Mutex);
+    }
+}
+
+OrbisFILE* PS4_SYSV_ABI internal__Foprep(const char* path, const char* mode, OrbisFILE* file,
+                                         s32 fd, s32 s_mode, s32 flag) {
+    if (file == nullptr) {
+        *Kernel::__Error() = POSIX_ENOMEM;
+    }
+
+    // Preserve mode and index
+    Libraries::Kernel::PthreadMutexT mtx = file->_Mutex;
+    Libraries::Kernel::PthreadMutexT* mtx_ptr = &file->_Mutex;
+    u8 file_index = file->_Idx;
+    u16 file_mode = file->_Mode & 0x80;
+
+    // Real library does a memcpy using a static global FILE object.
+    // This stored file is just zeros, with the only exception being a handle of -1.
+    memset(file, 0, sizeof(OrbisFILE));
+    file->_Handle = -1;
+
+    // Not sure what this magic is for, but I'll replicate it.
+    u8* ptr = &file->_Cbuf;
+    // Note: this field is supposed to be a pthread mutex.
+    // Since we don't export pthread HLEs for other functions, I'll avoid handling this for now.
+    file->_Mutex = nullptr;
+    file->_Idx = file_index;
+    file->_Buf = ptr;
+    file->_Bend = &file->unk2;
+    file->_Next = ptr;
+    file->_Rend = ptr;
+    file->_WRend = ptr;
+    file->_Wend = ptr;
+    file->_WWend = ptr;
+    file->_Rback = ptr;
+    file->_WRback = &file->unk1;
+
+    // Parse inputted mode string
+    const char* mode_str = mode;
+    u16 calc_mode = 0;
+    u16 access_mode = 0;
+    if (mode_str[0] == 'r') {
+        calc_mode = 1 | file_mode;
+    } else if (mode_str[0] == 'w') {
+        calc_mode = 0x1a | file_mode;
+    } else if (mode_str[0] == 'a') {
+        calc_mode = 0x16 | file_mode;
+    } else {
+        // Closes the file and returns EINVAL.
+        file->_Mode = file_mode;
+        if (flag == 0) {
+            internal__Mtxinit(mtx_ptr, nullptr);
+        } else {
+            file->_Mutex = mtx;
+            internal__Unlockfilelock(file);
+        }
+        internal_fclose(file);
+        *Kernel::__Error() = POSIX_EINVAL;
+        return nullptr;
+    }
+    file->_Mode = calc_mode;
+
+    do {
+        // This is all basically straight from decomp, need to cleanup at some point.
+        if (mode_str[1] == '+') {
+            file_mode = 3;
+            if ((~calc_mode & 3) == 0) {
+                break;
+            }
+        } else if (mode_str[1] != 'b') {
+            file_mode = 0x20;
+            if ((calc_mode & 0x20) != 0) {
+                break;
+            }
+        }
+        mode_str++;
+        calc_mode = file_mode | calc_mode;
+        file->_Mode = calc_mode;
+    } while (true);
+
+    if (path == nullptr && fd >= 0) {
+        // I guess this is for some internal behavior?
+        file->_Handle = fd;
+    } else {
+        fd = internal__Fopen(path, calc_mode, s_mode == 0x55);
+        file->_Handle = fd;
+    }
+
+    // Error case
+    if (fd < 0) {
+        // Closes the file, but ensures errno is unchanged.
+        if (flag == 0) {
+            internal__Mtxinit(mtx_ptr, nullptr);
+        } else {
+            file->_Mutex = mtx;
+            internal__Unlockfilelock(file);
+        }
+        s32 old_errno = *Kernel::__Error();
+        internal_fclose(file);
+        *Kernel::__Error() = old_errno;
+        return nullptr;
+    }
+
+    if (flag == 0) {
+        char mtx_name[0x20];
+        std::snprintf(mtx_name, 0x20, "FileFD:0x%08X", fd);
+        internal__Mtxinit(mtx_ptr, mtx_name);
+    } else {
+        file->_Mutex = mtx;
+    }
+    return file;
+}
+
+s32 PS4_SYSV_ABI internal__Fopen(const char* path, u16 mode, bool flag) {
+    u32 large_mode = mode;
+    u16 open_mode = 0600;
+    if (!flag) {
+        open_mode = 0666;
+    }
+    // Straight from decomp, should probably get cleaned up at some point.
+    s32 creat_flag = large_mode << 5 & 0x200;
+    s32 excl_flag = large_mode << 5 & 0x800;
+    s32 misc_flags = (large_mode & 8) * 0x80 + (large_mode & 4) * 2;
+    // Real library has an array for this, where large_mode & 3 is used as an index.
+    // That array has values [0, 0, 1, 2], so this call should match the result.
+    s32 access_flag = std::max<s32>((large_mode & 3) - 1, 0);
+    s32 open_flags = creat_flag | misc_flags | excl_flag | access_flag;
+    return Libraries::Kernel::posix_open(path, open_flags, open_mode);
+}
+
+OrbisFILE* PS4_SYSV_ABI internal_fopen(const char* path, const char* mode) {
+    std::scoped_lock lk{g_file_mtx};
+    LOG_INFO(Lib_LibcInternal, "called, path {}, mode {}", path, mode);
+    OrbisFILE* file = internal__Fofind();
+    return internal__Foprep(path, mode, file, -1, 0, 0);
+}
+
+s32 PS4_SYSV_ABI internal_fflush(OrbisFILE* file) {
+    if (file == nullptr) {
+        std::scoped_lock lk{g_file_mtx};
+        s32 fflush_result = 0;
+        for (auto& file : g_files) {
+            s32 res = internal_fflush(file.second);
+            if (res < 0) {
+                fflush_result = -1;
+            }
+        }
+        return fflush_result;
+    }
+    if ((file->_Mode & 0x2000) != 0) {
+        internal__Lockfilelock(file);
+        u16 file_mode = file->_Mode;
+        u8* file_buf_start = file->_Buf;
+        u8* file_buf_end = file->_Next;
+        while (file_buf_start < file_buf_end) {
+            u64 size_to_write = static_cast<u64>(file_buf_end - file_buf_start);
+            s32 write_bytes =
+                Libraries::Kernel::sceKernelWrite(file->_Handle, file_buf_start, size_to_write);
+            if (write_bytes < 1) {
+                file_buf_start = file->_Buf;
+                file->_Next = file_buf_start;
+                file->_Wend = file_buf_start;
+                file->_WWend = file_buf_start;
+                u8* off_mode = reinterpret_cast<u8*>(&file->_Mode) + 1;
+                *off_mode = *off_mode | 2;
+                internal__Unlockfilelock(file);
+                return -1;
+            }
+            file_buf_end = file->_Next;
+            file_buf_start += write_bytes;
+        }
+        file->_Next = file_buf_start;
+        file->_Wend = file_buf_start;
+        file->_WWend = file_buf_start;
+        file->_Mode = file_mode & 0xdfff;
+        internal__Unlockfilelock(file);
+    }
+    return 0;
+}
+
+s64 PS4_SYSV_ABI internal__Nnl(OrbisFILE* file, u8* val1, u8* val2) {
+    if (val1 < val2) {
+        return val2 - val1;
+    }
+    return 0;
+}
+
+s32 PS4_SYSV_ABI internal__Fspos(OrbisFILE* file, Orbisfpos_t* file_pos, s64 offset, s32 whence) {
+    if ((file->_Mode & 3) == 0) {
+        return -1;
+    }
+    if (internal_fflush(file) != 0) {
+        return -1;
+    }
+    if (whence >= 3) {
+        *Libraries::Kernel::__Error() = POSIX_EINVAL;
+        return -1;
+    }
+    if (file_pos != nullptr) {
+        offset = offset + file_pos->_Off;
+    }
+    if (whence == 1 && (file->_Mode & 0x1000) != 0) {
+        s64 val1 = internal__Nnl(file, file->_Rback, &file->_Cbuf);
+        u8* rsave_ptr = file->_Rsave;
+        if (rsave_ptr == nullptr) {
+            rsave_ptr = file->_Rend;
+        }
+        s64 val2 = internal__Nnl(file, file->_Next, rsave_ptr);
+        s64 val3 = internal__Nnl(file, file->_Next, file->_WRend);
+        offset = offset - (val1 + val2 + val3);
+    }
+    s64 result = 0;
+    if (whence == 2 || (whence == 1 && offset != 0) || (whence == 0 && offset != -1)) {
+        result = Libraries::Kernel::posix_lseek(file->_Handle, offset, whence);
+    }
+    if (result == -1) {
+        return -1;
+    }
+
+    u16 file_mode = file->_Mode;
+    if ((file_mode & 0x3000) != 0) {
+        u8* file_buf = file->_Buf;
+        file->_Next = file_buf;
+        file->_Rend = file_buf;
+        file->_WRend = file_buf;
+        file->_Wend = file_buf;
+        file->_WWend = file_buf;
+        file->_Rback = &file->_Cbuf;
+        file->_WRback = &file->unk1;
+        file->_Rsave = nullptr;
+    }
+    if (file_pos != nullptr) {
+        std::memcpy(&file->_Wstate, &file_pos->_Wstate, sizeof(Orbis_Mbstatet));
+    }
+    file->_Mode = file_mode & 0xceff;
+    return 0;
+}
+
+s32 PS4_SYSV_ABI internal_fseek(OrbisFILE* file, s64 offset, s32 whence) {
+    internal__Lockfilelock(file);
+    LOG_TRACE(Lib_LibcInternal, "called, file handle {:#x}, offset {:#x}, whence {:#x}",
+              file->_Handle, offset, whence);
+    s32 result = internal__Fspos(file, nullptr, offset, whence);
+    internal__Unlockfilelock(file);
+    return result;
+}
+
+s32 PS4_SYSV_ABI internal__Frprep(OrbisFILE* file) {
+    if (file->_Rend > file->_Next) {
+        return 1;
+    }
+    if ((file->_Mode & 0x100) != 0) {
+        return 0;
+    }
+    u16 mode = file->_Mode;
+    if ((mode & 0xa001) != 1) {
+        // Lot of magic here, might be valuable to figure out what this does.
+        file->_Mode = (((mode ^ 0x8000) >> 0xf) << 0xe) | mode | 0x200;
+        return -1;
+    }
+
+    u8* file_buf = file->_Buf;
+    if ((mode & 0x800) == 0 && file_buf == &file->_Cbuf) {
+        // Allocate a new file buffer, for now, we'll use host malloc to create it.
+        // When we have an HLE for malloc, that should be used instead.
+        u8* new_buffer = std::bit_cast<u8*>(std::malloc(0x10000));
+        if (new_buffer == nullptr) {
+            file->_Buf = file_buf;
+            file->_Bend = file_buf + 1;
+        } else {
+            file->_Mode = file->_Mode | 0x40;
+            file->_Buf = new_buffer;
+            file->_Bend = new_buffer + 0x10000;
+            file->_WRend = new_buffer;
+            file->_WWend = new_buffer;
+            file_buf = new_buffer;
+        }
+    }
+    file->_Next = file_buf;
+    file->_Rend = file_buf;
+    file->_Wend = file_buf;
+    // Intentional shrinking here, library treats value as 32-bit.
+    s32 read_result =
+        Libraries::Kernel::sceKernelRead(file->_Handle, file_buf, file->_Bend - file_buf);
+    if (read_result < 0) {
+        u8* off_mode = reinterpret_cast<u8*>(&file->_Mode) + 1;
+        *off_mode = *off_mode | 0x42;
+        return -1;
+    } else if (read_result != 0) {
+        file->_Mode = file->_Mode | 0x5000;
+        file->_Rend = file->_Rend + read_result;
+        return 1;
+    }
+    file->_Mode = (file->_Mode & 0xaeff) | 0x4100;
+    return 0;
+}
+
+u64 PS4_SYSV_ABI internal_fread(char* ptr, u64 size, u64 nmemb, OrbisFILE* file) {
+    if (size == 0 || nmemb == 0) {
+        return 0;
+    }
+    internal__Lockfilelock(file);
+    LOG_TRACE(Lib_LibcInternal, "called, file handle {:#x}, size {:#x}, nmemb {:#x}", file->_Handle,
+              size, nmemb);
+    s64 total_size = size * nmemb;
+    s64 remaining_size = total_size;
+    if ((file->_Mode & 0x4000) != 0) {
+        while (remaining_size != 0) {
+            u8* rback_ptr = file->_Rback;
+            if (&file->_Cbuf <= rback_ptr) {
+                break;
+            }
+            file->_Rback = rback_ptr + 1;
+            *ptr = *rback_ptr;
+            ptr++;
+            remaining_size--;
+        }
+    }
+
+    while (remaining_size != 0) {
+        u8* file_ptr = file->_Rsave;
+        if (file_ptr == nullptr) {
+            file_ptr = file->_Rend;
+        } else {
+            file->_Rend = file_ptr;
+            file->_Rsave = nullptr;
+        }
+        u8* src = file->_Next;
+        if (file_ptr <= src) {
+            s32 res = internal__Frprep(file);
+            if (res < 1) {
+                internal__Unlockfilelock(file);
+                return (total_size - remaining_size) / size;
+            }
+            src = file->_Next;
+            file_ptr = file->_Rend;
+        }
+        u64 copy_bytes = std::min<u64>(file_ptr - src, remaining_size);
+        std::memcpy(ptr, src, copy_bytes);
+        file->_Next += copy_bytes;
+        ptr += copy_bytes;
+        remaining_size -= copy_bytes;
+    }
+    internal__Unlockfilelock(file);
+    return (total_size - remaining_size) / size;
+}
+
+void PS4_SYSV_ABI internal__Fofree(OrbisFILE* file) {
+    u8* cbuf_ptr = &file->_Cbuf;
+    s8 trunc_mode = static_cast<s8>(file->_Mode);
+
+    file->_Mode = 0;
+    file->_Handle = -1;
+    file->_Buf = cbuf_ptr;
+    file->_Next = cbuf_ptr;
+    file->_Rend = cbuf_ptr;
+    file->_WRend = cbuf_ptr;
+    file->_Wend = cbuf_ptr;
+    file->_WWend = cbuf_ptr;
+    file->_Rback = cbuf_ptr;
+    file->_WRback = &file->unk1;
+    if (trunc_mode < 0) {
+        // Remove file from vector
+        g_files.erase(file->_Idx);
+        internal__Mtxdst(&file->_Mutex);
+        free(file);
+    }
+}
+
+s32 PS4_SYSV_ABI internal_fclose(OrbisFILE* file) {
+    if (file == nullptr) {
+        return -1;
+    }
+
+    LOG_INFO(Lib_LibcInternal, "called, file handle {:#x}", file->_Handle);
+    if ((file->_Mode & 3) == 0 || file->_Handle < 0) {
+        std::scoped_lock lk{g_file_mtx};
+        internal__Fofree(file);
+        *Libraries::Kernel::__Error() = POSIX_EBADF;
+    } else {
+        s32 fflush_result = internal_fflush(file);
+        std::scoped_lock lk{g_file_mtx};
+        if ((file->_Mode & 0x40) != 0) {
+            std::free(file->_Buf);
+        }
+        file->_Buf = nullptr;
+        s32 close_result = Libraries::Kernel::posix_close(file->_Handle);
+        internal__Fofree(file);
+        // Need to figure out what exactly this means.
+        return ~-(close_result == 0) | fflush_result;
+    }
+    return 0;
+}
+
 void RegisterlibSceLibcInternalIo(Core::Loader::SymbolsResolver* sym) {
     LIB_FUNCTION("eLdDw6l0-bU", "libSceLibcInternal", 1, "libSceLibcInternal", internal_snprintf);
+    LIB_FUNCTION("MUjC4lbHrK4", "libSceLibcInternal", 1, "libSceLibcInternal", internal_fflush);
+    LIB_FUNCTION("xGT4Mc55ViQ", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Fofind);
+    LIB_FUNCTION("dREVnZkAKRE", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Foprep);
+    LIB_FUNCTION("sQL8D-jio7U", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Fopen);
+    LIB_FUNCTION("A+Y3xfrWLLo", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Fspos);
+    LIB_FUNCTION("Ss3108pBuZY", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Nnl);
+    LIB_FUNCTION("9s3P+LCvWP8", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Frprep);
+    LIB_FUNCTION("jVDuvE3s5Bs", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Fofree);
+    LIB_FUNCTION("vZkmJmvqueY", "libSceLibcInternal", 1, "libSceLibcInternal",
+                 internal__Lockfilelock);
+    LIB_FUNCTION("0x7rx8TKy2Y", "libSceLibcInternal", 1, "libSceLibcInternal",
+                 internal__Unlockfilelock);
 }
+
+void ForceRegisterlibSceLibcInternalIo(Core::Loader::SymbolsResolver* sym) {
+    // Goal is to be minimally intrusive here to allow LLE for printf/stdout writes.
+    LIB_FUNCTION("xeYO4u7uyJ0", "libSceLibcInternal", 1, "libSceLibcInternal", internal_fopen);
+    LIB_FUNCTION("rQFVBXp-Cxg", "libSceLibcInternal", 1, "libSceLibcInternal", internal_fseek);
+    LIB_FUNCTION("lbB+UlZqVG0", "libSceLibcInternal", 1, "libSceLibcInternal", internal_fread);
+    LIB_FUNCTION("uodLYyUip20", "libSceLibcInternal", 1, "libSceLibcInternal", internal_fclose);
+}
+
 } // namespace Libraries::LibcInternal
\ No newline at end of file
diff --git a/src/core/libraries/libc_internal/libc_internal_io.h b/src/core/libraries/libc_internal/libc_internal_io.h
index f5291526b..27915d8fa 100644
--- a/src/core/libraries/libc_internal/libc_internal_io.h
+++ b/src/core/libraries/libc_internal/libc_internal_io.h
@@ -3,12 +3,96 @@
 
 #pragma once
 
+#include <mutex>
 #include "common/types.h"
+#include "core/libraries/kernel/threads.h"
 
 namespace Core::Loader {
 class SymbolsResolver;
 }
 
 namespace Libraries::LibcInternal {
+
+static std::recursive_mutex g_file_mtx{};
+
+union Orbis__mbstate_t {
+    u8 __mbstate8[128];
+    s64 _mbstateL;
+};
+
+struct Orbis_Mbstatet {
+    u64 _Wchar;
+    u16 _Byte, _State;
+    s32 : 32;
+};
+
+struct Orbisfpos_t {
+    s64 _Off;
+    Orbis_Mbstatet _Wstate;
+};
+
+struct Orbis__sbuf {
+    u8* _base;
+    s32 _size;
+};
+
+struct OrbisFILE {
+    u16 _Mode;
+    u8 _Idx;
+    s32 _Handle;
+    u8 *_Buf, *_Bend, *_Next;
+    u8 *_Rend, *_Wend, *_Rback;
+    u16 *_WRback, _WBack[2];
+    u16 unk1;
+    u8 *_Rsave, *_WRend, *_WWend;
+    Orbis_Mbstatet _Wstate;
+    u8* _Tmpnam;
+    u8 _Back[6], _Cbuf;
+    u8 unk2;
+    Libraries::Kernel::PthreadMutexT _Mutex;
+    u8* _p;
+    s32 _r;
+    s32 _w;
+    s16 _flags;
+    s16 _file;
+    Orbis__sbuf _bf;
+    s32 _lbfsize;
+    void* _cookie;
+    s32 PS4_SYSV_ABI (*_close)(void*);
+    s32 PS4_SYSV_ABI (*_read)(void*, char*, s32);
+    Orbisfpos_t PS4_SYSV_ABI (*_seek)(void*, Orbisfpos_t, s32);
+    s32 (*_write)(void*, const char*, s32);
+    Orbis__sbuf _ub;
+    u8* _up;
+    s32 _ur;
+    u8 _ubuf[3];
+    u8 _nbuf[1];
+    Orbis__sbuf _lb;
+    s32 _blksize;
+    Orbisfpos_t _offset;
+    void* _fl_mutex;
+    void* _fl_owner;
+    s32 _fl_count;
+    s32 _orientation;
+    Orbis__mbstate_t _mbstate;
+};
+
+s32 PS4_SYSV_ABI internal_snprintf(char* s, u64 n, VA_ARGS);
+void PS4_SYSV_ABI internal__Lockfilelock(OrbisFILE* file);
+void PS4_SYSV_ABI internal__Unlockfilelock(OrbisFILE* file);
+OrbisFILE* PS4_SYSV_ABI internal__Fofind();
+OrbisFILE* PS4_SYSV_ABI internal__Foprep(const char* path, const char* mode, OrbisFILE* file,
+                                         s32 fd, s32 flag1, s32 flag2);
+s32 PS4_SYSV_ABI internal__Fopen(const char* path, u16 mode, bool flag);
+OrbisFILE* PS4_SYSV_ABI internal_fopen(const char* path, const char* mode);
+s64 PS4_SYSV_ABI internal__Nnl(OrbisFILE* file, u8* val1, u8* val2);
+s32 PS4_SYSV_ABI internal__Fspos(OrbisFILE* file, Orbisfpos_t* file_pos, s64 offset, s32 whence);
+s32 PS4_SYSV_ABI internal_fflush(OrbisFILE* file);
+s32 PS4_SYSV_ABI internal_fseek(OrbisFILE* file, s64 offset, s32 whence);
+s32 PS4_SYSV_ABI internal__Frprep(OrbisFILE* file);
+u64 PS4_SYSV_ABI internal_fread(char* ptr, u64 size, u64 nmemb, OrbisFILE* file);
+s32 PS4_SYSV_ABI internal_fclose(OrbisFILE* file);
+
 void RegisterlibSceLibcInternalIo(Core::Loader::SymbolsResolver* sym);
+void ForceRegisterlibSceLibcInternalIo(Core::Loader::SymbolsResolver* sym);
 } // namespace Libraries::LibcInternal
\ No newline at end of file
diff --git a/src/core/libraries/libc_internal/libc_internal_threads.cpp b/src/core/libraries/libc_internal/libc_internal_threads.cpp
new file mode 100644
index 000000000..2d8ddaccb
--- /dev/null
+++ b/src/core/libraries/libc_internal/libc_internal_threads.cpp
@@ -0,0 +1,65 @@
+// SPDX-FileCopyrightText: Copyright 2026 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "core/libraries/kernel/threads.h"
+#include "core/libraries/libc_internal/libc_internal_threads.h"
+#include "core/libraries/libs.h"
+
+namespace Libraries::LibcInternal {
+
+void getMutexName(char* buf, u64 size, const char* name) {
+    if (name != nullptr) {
+        std::snprintf(buf, size, "SceLibcI_%s", name);
+    } else {
+        std::snprintf(buf, size, "SceLibcI");
+    }
+}
+
+s32 PS4_SYSV_ABI internal__Mtxinit(Libraries::Kernel::PthreadMutexT* mtx, const char* name) {
+    char mtx_name[0x20];
+    getMutexName(mtx_name, sizeof(mtx_name), name);
+
+    Libraries::Kernel::PthreadMutexAttrT attr{};
+    s32 result = Libraries::Kernel::posix_pthread_mutexattr_init(&attr);
+    if (result != 0) {
+        return 1;
+    }
+
+    result = Libraries::Kernel::posix_pthread_mutexattr_settype(
+        &attr, Libraries::Kernel::PthreadMutexType::Recursive);
+    if (result == 0) {
+        s32 mtx_init_result = Libraries::Kernel::scePthreadMutexInit(mtx, &attr, mtx_name);
+        result = Libraries::Kernel::posix_pthread_mutexattr_destroy(&attr);
+        if (mtx_init_result == 0 && result == 0) {
+            return 0;
+        }
+    } else {
+        Libraries::Kernel::posix_pthread_mutexattr_destroy(&attr);
+    }
+
+    return 1;
+}
+
+s32 PS4_SYSV_ABI internal__Mtxlock(Libraries::Kernel::PthreadMutexT* mtx) {
+    s32 result = Libraries::Kernel::posix_pthread_mutex_lock(mtx);
+    return result != 0;
+}
+
+s32 PS4_SYSV_ABI internal__Mtxunlock(Libraries::Kernel::PthreadMutexT* mtx) {
+    s32 result = Libraries::Kernel::posix_pthread_mutex_unlock(mtx);
+    return result != 0;
+}
+
+s32 PS4_SYSV_ABI internal__Mtxdst(Libraries::Kernel::PthreadMutexT* mtx) {
+    s32 result = Libraries::Kernel::posix_pthread_mutex_destroy(mtx);
+    return result != 0;
+}
+
+void RegisterlibSceLibcInternalThreads(Core::Loader::SymbolsResolver* sym) {
+    LIB_FUNCTION("z7STeF6abuU", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Mtxinit);
+    LIB_FUNCTION("pE4Ot3CffW0", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Mtxlock);
+    LIB_FUNCTION("cMwgSSmpE5o", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Mtxunlock);
+    LIB_FUNCTION("LaPaA6mYA38", "libSceLibcInternal", 1, "libSceLibcInternal", internal__Mtxdst);
+}
+
+} // namespace Libraries::LibcInternal
\ No newline at end of file
diff --git a/src/core/libraries/libc_internal/libc_internal_threads.h b/src/core/libraries/libc_internal/libc_internal_threads.h
new file mode 100644
index 000000000..74e6d41b1
--- /dev/null
+++ b/src/core/libraries/libc_internal/libc_internal_threads.h
@@ -0,0 +1,22 @@
+// SPDX-FileCopyrightText: Copyright 2026 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <mutex>
+#include "common/types.h"
+#include "core/libraries/kernel/threads.h"
+
+namespace Core::Loader {
+class SymbolsResolver;
+}
+
+namespace Libraries::LibcInternal {
+
+s32 PS4_SYSV_ABI internal__Mtxinit(Libraries::Kernel::PthreadMutexT* mtx, const char* name);
+s32 PS4_SYSV_ABI internal__Mtxlock(Libraries::Kernel::PthreadMutexT* mtx);
+s32 PS4_SYSV_ABI internal__Mtxunlock(Libraries::Kernel::PthreadMutexT* mtx);
+s32 PS4_SYSV_ABI internal__Mtxdst(Libraries::Kernel::PthreadMutexT* mtx);
+
+void RegisterlibSceLibcInternalThreads(Core::Loader::SymbolsResolver* sym);
+} // namespace Libraries::LibcInternal
\ No newline at end of file
diff --git a/src/core/libraries/libs.cpp b/src/core/libraries/libs.cpp
index 67c3d4b7d..eebb991dc 100644
--- a/src/core/libraries/libs.cpp
+++ b/src/core/libraries/libs.cpp
@@ -80,6 +80,7 @@ namespace Libraries {
 void InitHLELibs(Core::Loader::SymbolsResolver* sym) {
     LOG_INFO(Lib_Kernel, "Initializing HLE libraries");
     Libraries::Kernel::RegisterLib(sym);
+    Libraries::LibcInternal::ForceRegisterLib(sym);
     Libraries::GnmDriver::RegisterLib(sym);
     Libraries::VideoOut::RegisterLib(sym);
     Libraries::UserService::RegisterLib(sym);