diff --git a/CMakeLists.txt b/CMakeLists.txt
index edb6cf06f9..058fb31156 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -93,18 +93,22 @@ if(NOT SwiftFoundation_MODULE_TRIPLE)
 endif()
 
 # System dependencies
-find_package(dispatch CONFIG)
-if(NOT dispatch_FOUND)
-    if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Android")
-        set(DEFAULT_DISPATCH_INCLUDE_PATH "/usr/lib/swift")
-    elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows")
-        set(DEFAULT_DISPATCH_INCLUDE_PATH "$ENV{SDKROOT}usr/include")
+
+# We know libdispatch is always unavailable on WASI
+if(NOT CMAKE_SYSTEM_NAME STREQUAL WASI)
+    find_package(dispatch CONFIG)
+    if(NOT dispatch_FOUND)
+        if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Android")
+            set(DEFAULT_DISPATCH_INCLUDE_PATH "/usr/lib/swift")
+        elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+            set(DEFAULT_DISPATCH_INCLUDE_PATH "$ENV{SDKROOT}usr/include")
+        endif()
+        set(DISPATCH_INCLUDE_PATH "${DEFAULT_DISPATCH_INCLUDE_PATH}" CACHE STRING "A path to where you can find libdispatch headers")
+        message("-- dispatch_DIR not found, using dispatch from SDK at ${DISPATCH_INCLUDE_PATH}")
+        list(APPEND _Foundation_common_build_flags
+            "-I${DISPATCH_INCLUDE_PATH}"
+            "-I${DISPATCH_INCLUDE_PATH}/Block")
     endif()
-    set(DISPATCH_INCLUDE_PATH "${DEFAULT_DISPATCH_INCLUDE_PATH}" CACHE STRING "A path to where you can find libdispatch headers")
-    message("-- dispatch_DIR not found, using dispatch from SDK at ${DISPATCH_INCLUDE_PATH}")
-    list(APPEND _Foundation_common_build_flags
-        "-I${DISPATCH_INCLUDE_PATH}"
-        "-I${DISPATCH_INCLUDE_PATH}/Block")
 endif()
 find_package(LibXml2 REQUIRED)
 find_package(CURL REQUIRED)
@@ -113,7 +117,6 @@ find_package(CURL REQUIRED)
 list(APPEND _Foundation_common_build_flags
     "-DDEPLOYMENT_RUNTIME_SWIFT"
     "-DCF_BUILDING_CF"
-    "-DDEPLOYMENT_ENABLE_LIBDISPATCH"
     "-DHAVE_STRUCT_TIMESPEC"
     "-Wno-shorten-64-to-32"
     "-Wno-deprecated-declarations"
@@ -126,16 +129,10 @@ list(APPEND _Foundation_common_build_flags
     "-Wno-switch"
     "-fblocks")
 
-if(CMAKE_SYSTEM_NAME STREQUAL "WASI")
-  list(APPEND _Foundation_common_build_flags
-    "-D_WASI_EMULATED_SIGNAL"
-    "-DHAVE_STRLCPY"
-    "-DHAVE_STRLCAT"
-  )
-else()
-  list(APPEND _Foundation_common_build_flags
-    "-DSWIFT_CORELIBS_FOUNDATION_HAS_THREADS"
-  )
+if(NOT CMAKE_SYSTEM_NAME STREQUAL WASI)
+    list(APPEND _Foundation_common_build_flags
+        "-DDEPLOYMENT_ENABLE_LIBDISPATCH"
+        "-DSWIFT_CORELIBS_FOUNDATION_HAS_THREADS")
 endif()
 
 if(NOT "${CMAKE_C_SIMULATE_ID}" STREQUAL "MSVC")
@@ -168,16 +165,17 @@ list(APPEND _Foundation_swift_build_flags
     "-Xfrontend"
     "-require-explicit-sendable")
 
-if(CMAKE_SYSTEM_NAME STREQUAL "WASI")
-  list(APPEND _Foundation_swift_build_flags
-    "-D_WASI_EMULATED_SIGNAL"
-    "-DHAVE_STRLCPY"
-    "-DHAVE_STRLCAT"
-  )
+if(CMAKE_SYSTEM_NAME STREQUAL WASI)
+    # Enable wasi-libc emulation features
+    set(WASI_EMULATION_DEFS _WASI_EMULATED_MMAN _WASI_EMULATED_SIGNAL _WASI_EMULATED_PROCESS_CLOCKS)
+    foreach(def ${WASI_EMULATION_DEFS})
+        list(APPEND _Foundation_swift_build_flags "SHELL:-Xcc -D${def}")
+        list(APPEND _Foundation_common_build_flags "-D${def}")
+    endforeach()
 else()
-  list(APPEND _Foundation_swift_build_flags
-    "-DSWIFT_CORELIBS_FOUNDATION_HAS_THREADS"
-  )
+    # Assume we have threads on other platforms
+    list(APPEND _Foundation_swift_build_flags
+        "-DSWIFT_CORELIBS_FOUNDATION_HAS_THREADS")
 endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Android")
diff --git a/Package.swift b/Package.swift
index 1477aefd00..dc86631a79 100644
--- a/Package.swift
+++ b/Package.swift
@@ -39,14 +39,12 @@ let coreFoundationBuildSettings: [CSetting] = [
     .headerSearchPath("internalInclude"),
     .define("DEBUG", .when(configuration: .debug)),
     .define("CF_BUILDING_CF"),
-    .define("DEPLOYMENT_ENABLE_LIBDISPATCH"),
+    .define("DEPLOYMENT_ENABLE_LIBDISPATCH", .when(platforms: platformsWithThreads)),
     .define("DEPLOYMENT_RUNTIME_SWIFT"),
     .define("HAVE_STRUCT_TIMESPEC"),
     .define("SWIFT_CORELIBS_FOUNDATION_HAS_THREADS", .when(platforms: platformsWithThreads)),
     .define("_GNU_SOURCE", .when(platforms: [.linux, .android])),
     .define("_WASI_EMULATED_SIGNAL", .when(platforms: [.wasi])),
-    .define("HAVE_STRLCPY", .when(platforms: [.wasi])),
-    .define("HAVE_STRLCAT", .when(platforms: [.wasi])),
     .unsafeFlags([
         "-Wno-shorten-64-to-32",
         "-Wno-deprecated-declarations",
@@ -78,8 +76,6 @@ let interfaceBuildSettings: [CSetting] = [
     .define("SWIFT_CORELIBS_FOUNDATION_HAS_THREADS", .when(platforms: platformsWithThreads)),
     .define("_GNU_SOURCE", .when(platforms: [.linux, .android])),
     .define("_WASI_EMULATED_SIGNAL", .when(platforms: [.wasi])),
-    .define("HAVE_STRLCPY", .when(platforms: [.wasi])),
-    .define("HAVE_STRLCAT", .when(platforms: [.wasi])),
     .unsafeFlags([
         "-Wno-shorten-64-to-32",
         "-Wno-deprecated-declarations",
@@ -161,7 +157,8 @@ let package = Package(
                 .product(name: "FoundationEssentials", package: "swift-foundation"),
                 "Foundation",
                 "CoreFoundation",
-                "_CFXMLInterface"
+                "_CFXMLInterface",
+                .target(name: "BlocksRuntime", condition: .when(platforms: [.wasi])),
             ],
             path: "Sources/FoundationXML",
             exclude: [
@@ -187,6 +184,7 @@ let package = Package(
             name: "CoreFoundation",
             dependencies: [
                 .product(name: "_FoundationICU", package: "swift-foundation-icu"),
+                .target(name: "BlocksRuntime", condition: .when(platforms: [.wasi])),
             ],
             path: "Sources/CoreFoundation",
             exclude: [
@@ -195,6 +193,17 @@ let package = Package(
             ],
             cSettings: coreFoundationBuildSettings
         ),
+        .target(
+            name: "BlocksRuntime",
+            path: "Sources/CoreFoundation/BlockRuntime",
+            exclude: [
+                "CMakeLists.txt"
+            ],
+            cSettings: [
+                // For CFTargetConditionals.h
+                .headerSearchPath("../include"),
+            ]
+        ),
         .target(
             name: "_CFXMLInterface",
             dependencies: [
diff --git a/Sources/CMakeLists.txt b/Sources/CMakeLists.txt
index 0ee266a4bc..29b9244065 100644
--- a/Sources/CMakeLists.txt
+++ b/Sources/CMakeLists.txt
@@ -14,10 +14,14 @@
 
 add_subdirectory(CoreFoundation)
 add_subdirectory(_CFXMLInterface)
-add_subdirectory(_CFURLSessionInterface)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL "WASI")
+    add_subdirectory(_CFURLSessionInterface)
+endif()
 add_subdirectory(Foundation)
 add_subdirectory(FoundationXML)
-add_subdirectory(FoundationNetworking)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL "WASI")
+    add_subdirectory(FoundationNetworking)
+endif()
 if(FOUNDATION_BUILD_TOOLS)
 	add_subdirectory(plutil)
 endif()
diff --git a/Sources/CoreFoundation/BlockRuntime/CMakeLists.txt b/Sources/CoreFoundation/BlockRuntime/CMakeLists.txt
new file mode 100644
index 0000000000..47779784e7
--- /dev/null
+++ b/Sources/CoreFoundation/BlockRuntime/CMakeLists.txt
@@ -0,0 +1,29 @@
+##===----------------------------------------------------------------------===##
+##
+## This source file is part of the Swift open source project
+##
+## Copyright (c) 2024 Apple Inc. and the Swift project authors
+## Licensed under Apache License v2.0
+##
+## See LICENSE.txt for license information
+## See CONTRIBUTORS.md for the list of Swift project authors
+##
+## SPDX-License-Identifier: Apache-2.0
+##
+##===----------------------------------------------------------------------===##
+
+# Build the vendored version of the BlocksRuntime library, which is used by
+# platforms that don't support libdispatch.
+
+# Build the BlocksRuntime as an object library, shipped as a part
+# of libCoreFoundation.
+add_library(BlocksRuntime OBJECT
+    data.c
+    runtime.c)
+
+target_include_directories(BlocksRuntime PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    # For CFTargetConditionals.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/../include)
+
+set_property(GLOBAL APPEND PROPERTY Foundation_EXPORTS BlocksRuntime)
diff --git a/Sources/CoreFoundation/CFBundle.c b/Sources/CoreFoundation/CFBundle.c
index 05afe9888e..607c7bd925 100644
--- a/Sources/CoreFoundation/CFBundle.c
+++ b/Sources/CoreFoundation/CFBundle.c
@@ -600,7 +600,7 @@ CFBundleRef CFBundleGetBundleWithIdentifier(CFStringRef bundleID) {
 #if TARGET_OS_WASI
     hint = NULL;
 #else
-    hint = __builtin_frame_address(0);
+    hint = __builtin_return_address(0);
 #endif
     return _CFBundleGetBundleWithIdentifier(bundleID, hint);
 }
diff --git a/Sources/CoreFoundation/CFString.c b/Sources/CoreFoundation/CFString.c
index 94a6c86d15..f8899e1589 100644
--- a/Sources/CoreFoundation/CFString.c
+++ b/Sources/CoreFoundation/CFString.c
@@ -35,7 +35,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
-#if TARGET_OS_MAC || TARGET_OS_LINUX || TARGET_OS_BSD
+#if TARGET_OS_MAC || TARGET_OS_LINUX || TARGET_OS_BSD || TARGET_OS_WASI
 #include <unistd.h>
 #endif
 #if TARGET_OS_WASI
diff --git a/Sources/CoreFoundation/CMakeLists.txt b/Sources/CoreFoundation/CMakeLists.txt
index e366005f72..71e7c2f00d 100644
--- a/Sources/CoreFoundation/CMakeLists.txt
+++ b/Sources/CoreFoundation/CMakeLists.txt
@@ -118,6 +118,13 @@ target_link_libraries(CoreFoundation
         _FoundationICU
         dispatch)
 
+if(CMAKE_SYSTEM_NAME STREQUAL WASI)
+    # On WASI, we use vendored BlocksRuntime instead of the one from libdispatch
+    add_subdirectory(BlockRuntime)
+    # Add BlocksRuntime object library to CoreFoundation static archive
+    target_link_libraries(CoreFoundation PRIVATE BlocksRuntime)
+endif()
+
 set_property(GLOBAL APPEND PROPERTY Foundation_EXPORTS CoreFoundation)
 
 # Copy Headers to known directory for direct client (XCTest) test builds
diff --git a/Sources/CoreFoundation/include/CoreFoundation.h b/Sources/CoreFoundation/include/CoreFoundation.h
index a66e7e614d..64313f0b9f 100644
--- a/Sources/CoreFoundation/include/CoreFoundation.h
+++ b/Sources/CoreFoundation/include/CoreFoundation.h
@@ -58,9 +58,7 @@
 #include "CFLocale.h"
 #include "CFNumber.h"
 #include "CFNumberFormatter.h"
-#if !TARGET_OS_WASI
 #include "CFPreferences.h"
-#endif
 #include "CFPropertyList.h"
 #include "CFSet.h"
 #include "CFString.h"
@@ -76,13 +74,17 @@
 
 #include "ForSwiftFoundationOnly.h"
 
-#if TARGET_OS_OSX || TARGET_OS_IPHONE || TARGET_OS_WIN32 || TARGET_OS_LINUX
+#if TARGET_OS_OSX || TARGET_OS_IPHONE || TARGET_OS_WIN32 || TARGET_OS_LINUX || TARGET_OS_WASI
+#  if !TARGET_OS_WASI
 #include "CFMessagePort.h"
 #include "CFPlugIn.h"
+#  endif
 #include "CFRunLoop.h"
 #include "CFStream.h"
+#  if !TARGET_OS_WASI
 #include "CFSocket.h"
 #include "CFMachPort.h"
+#  endif
 
 #include "CFAttributedString.h"
 #include "CFNotificationCenter.h"
diff --git a/Sources/CoreFoundation/internalInclude/CoreFoundation_Prefix.h b/Sources/CoreFoundation/internalInclude/CoreFoundation_Prefix.h
index 9ef8f64a6c..dea3b57537 100644
--- a/Sources/CoreFoundation/internalInclude/CoreFoundation_Prefix.h
+++ b/Sources/CoreFoundation/internalInclude/CoreFoundation_Prefix.h
@@ -109,6 +109,11 @@ typedef char * Class;
 #include <pthread.h>
 #endif
 
+#if TARGET_OS_WASI
+#define HAVE_STRLCPY 1
+#define HAVE_STRLCAT 1
+#endif
+
 #if TARGET_OS_WIN32
 #define BOOL WINDOWS_BOOL
 
diff --git a/Sources/_CFXMLInterface/CMakeLists.txt b/Sources/_CFXMLInterface/CMakeLists.txt
index d6e63a3f59..9ca0c27900 100644
--- a/Sources/_CFXMLInterface/CMakeLists.txt
+++ b/Sources/_CFXMLInterface/CMakeLists.txt
@@ -20,7 +20,7 @@ target_include_directories(_CFXMLInterface
         ../CoreFoundation/include
     PRIVATE
         ../CoreFoundation/internalInclude
-        /usr/include/libxml2/)
+        ${LIBXML2_INCLUDE_DIR})
 
 target_compile_options(_CFXMLInterface INTERFACE
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xcc -fmodule-map-file=${CMAKE_CURRENT_SOURCE_DIR}/../CoreFoundation/include/module.modulemap>"
@@ -33,6 +33,10 @@ target_link_libraries(_CFXMLInterface PRIVATE
     dispatch
     LibXml2::LibXml2)
 
+if(CMAKE_SYSTEM_NAME STREQUAL WASI)
+    target_link_libraries(_CFXMLInterface PRIVATE BlocksRuntime)
+endif()
+
 if(NOT BUILD_SHARED_LIBS)
     set_property(GLOBAL APPEND PROPERTY Foundation_EXPORTS _CFXMLInterface)
     install(TARGETS _CFXMLInterface