diff --git a/AK/Platform.h b/AK/Platform.h
index 14a81609080..1a4e8a2620c 100644
--- a/AK/Platform.h
+++ b/AK/Platform.h
@@ -33,6 +33,10 @@
 #    define AK_OS_BSD_GENERIC
 #endif
 
+#if defined(_WIN32) || defined(_WIN64)
+#    define AK_OS_WINDOWS
+#endif
+
 // FIXME: Remove clang-format suppression after https://github.com/llvm/llvm-project/issues/56602 resolved
 // clang-format off
 #if defined(__ANDROID__)
@@ -127,7 +131,11 @@ extern "C" {
 #    endif
 #endif
 
-#ifdef AK_OS_BSD_GENERIC
+#if defined(AK_OS_WINDOWS)
+#    define CLOCK_MONOTONIC_COARSE CLOCK_MONOTONIC
+#endif
+
+#if defined(AK_OS_BSD_GENERIC)
 #    define CLOCK_MONOTONIC_COARSE CLOCK_MONOTONIC
 #    define CLOCK_REALTIME_COARSE CLOCK_REALTIME
 #endif
diff --git a/AK/Random.h b/AK/Random.h
index fe5961c3fa1..4767c93e5a2 100644
--- a/AK/Random.h
+++ b/AK/Random.h
@@ -21,6 +21,11 @@
 #    include <sys/random.h>
 #endif
 
+#if defined(AK_OS_WINDOWS)
+#    include <random>
+#    include <unistd.h>
+#endif
+
 namespace AK {
 
 inline void fill_with_random([[maybe_unused]] void* buffer, [[maybe_unused]] size_t length)
@@ -30,6 +35,11 @@ inline void fill_with_random([[maybe_unused]] void* buffer, [[maybe_unused]] siz
 #elif defined(OSS_FUZZ)
 #elif defined(__unix__) or defined(AK_OS_MACOS)
     [[maybe_unused]] int rc = getentropy(buffer, length);
+#else
+    char* char_buffer = static_cast<char*>(buffer);
+    for (size_t i = 0; i < length; i++) {
+        char_buffer[i] = std::rand();
+    }
 #endif
 }
 
diff --git a/AK/Singleton.h b/AK/Singleton.h
index a0c6fa32902..c74b3324697 100644
--- a/AK/Singleton.h
+++ b/AK/Singleton.h
@@ -13,6 +13,12 @@
 #    include <Kernel/Arch/Processor.h>
 #    include <Kernel/Arch/ScopedCritical.h>
 #    include <Kernel/Locking/SpinlockProtected.h>
+#elif defined(AK_OS_WINDOWS)
+// Forward declare to avoid pulling Windows.h into every file in existence.
+extern "C" __declspec(dllimport) void __stdcall Sleep(unsigned long);
+#    ifndef sched_yield
+#        define sched_yield() Sleep(0)
+#    endif
 #else
 #    include <sched.h>
 #endif
diff --git a/AK/Time.cpp b/AK/Time.cpp
index bb01b1e9070..6eb9d2bdedb 100644
--- a/AK/Time.cpp
+++ b/AK/Time.cpp
@@ -179,7 +179,10 @@ timespec Time::to_timespec() const
 timeval Time::to_timeval() const
 {
     VERIFY(m_nanoseconds < 1'000'000'000);
-    return { static_cast<time_t>(m_seconds), static_cast<suseconds_t>(m_nanoseconds) / 1000 };
+    // This is done because winsock defines tv_sec and tv_usec as long, and Linux64 as long int.
+    using sec_type = decltype(declval<timeval>().tv_sec);
+    using usec_type = decltype(declval<timeval>().tv_usec);
+    return { static_cast<sec_type>(m_seconds), static_cast<usec_type>(m_nanoseconds) / 1000 };
 }
 
 Time Time::operator+(Time const& other) const
diff --git a/AK/Time.h b/AK/Time.h
index d64e1b9ac5a..8e5d128269d 100644
--- a/AK/Time.h
+++ b/AK/Time.h
@@ -16,6 +16,10 @@
 struct timeval;
 struct timespec;
 
+#if defined(AK_OS_WINDOWS)
+#    include <time.h>
+#endif
+
 namespace AK {
 
 // Concept to detect types which look like timespec without requiring the type.
diff --git a/AK/Types.h b/AK/Types.h
index 7e8100cc46f..06e35d4d9cb 100644
--- a/AK/Types.h
+++ b/AK/Types.h
@@ -50,6 +50,10 @@ using pid_t = int;
 using __ptrdiff_t = __PTRDIFF_TYPE__;
 #    endif
 
+#    if defined(AK_OS_WINDOWS)
+using ssize_t = MakeSigned<size_t>;
+using mode_t = unsigned short;
+#    endif
 #endif
 
 using FlatPtr = Conditional<sizeof(void*) == 8, u64, u32>;
diff --git a/Meta/Lagom/CMakeLists.txt b/Meta/Lagom/CMakeLists.txt
index e680c708a9f..4635207a5b3 100644
--- a/Meta/Lagom/CMakeLists.txt
+++ b/Meta/Lagom/CMakeLists.txt
@@ -265,6 +265,12 @@ if (ANDROID)
     list(REMOVE_ITEM LIBCORE_SOURCES "${CMAKE_CURRENT_LIST_DIR}/../../Userland/Libraries/LibCore/Account.cpp")
     list(REMOVE_ITEM LIBCORE_SOURCES "${CMAKE_CURRENT_LIST_DIR}/../../Userland/Libraries/LibCore/LocalServer.cpp")
 endif()
+if (WIN32)
+    list(REMOVE_ITEM LIBCORE_SOURCES "${CMAKE_CURRENT_LIST_DIR}/../../Userland/Libraries/LibCore/Account.cpp")
+    list(REMOVE_ITEM LIBCORE_SOURCES "${CMAKE_CURRENT_LIST_DIR}/../../Userland/Libraries/LibCore/FilePermissionsMask.cpp")
+    list(REMOVE_ITEM LIBCORE_SOURCES "${CMAKE_CURRENT_LIST_DIR}/../../Userland/Libraries/LibCore/Group.cpp")
+    list(REMOVE_ITEM LIBCORE_SOURCES "${CMAKE_CURRENT_LIST_DIR}/../../Userland/Libraries/LibCore/GetPassword.cpp")
+endif()
 lagom_lib(Core core
     SOURCES ${AK_SOURCES} ${LIBCORE_SOURCES}
     LIBS Threads::Threads