diff --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
index 8aab9a790f24a..78c88db143ce1 100644
--- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
+++ b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
@@ -4982,10 +4982,13 @@ OpenMPIRBuilder::getOrCreateInternalVariable(Type *Ty, const StringRef &Name,
     // variable for possibly changing that to internal or private, or maybe
     // create different versions of the function for different OMP internal
     // variables.
-    auto *GV = new GlobalVariable(
-        M, Ty, /*IsConstant=*/false, GlobalValue::CommonLinkage,
-        Constant::getNullValue(Ty), Elem.first(),
-        /*InsertBefore=*/nullptr, GlobalValue::NotThreadLocal, AddressSpace);
+    auto Linkage = this->M.getTargetTriple().rfind("wasm32") == 0
+                       ? GlobalValue::ExternalLinkage
+                       : GlobalValue::CommonLinkage;
+    auto *GV = new GlobalVariable(M, Ty, /*IsConstant=*/false, Linkage,
+                                  Constant::getNullValue(Ty), Elem.first(),
+                                  /*InsertBefore=*/nullptr,
+                                  GlobalValue::NotThreadLocal, AddressSpace);
     const DataLayout &DL = M.getDataLayout();
     const llvm::Align TypeAlign = DL.getABITypeAlign(Ty);
     const llvm::Align PtrAlign = DL.getPointerABIAlignment(AddressSpace);
diff --git a/openmp/CMakeLists.txt b/openmp/CMakeLists.txt
index 13e65bf70b5bb..307c8dbbc0c3b 100644
--- a/openmp/CMakeLists.txt
+++ b/openmp/CMakeLists.txt
@@ -94,7 +94,7 @@ set(ENABLE_LIBOMPTARGET ON)
 # Since the device plugins are only supported on Linux anyway,
 # there is no point in trying to compile libomptarget on other OSes.
 # 32-bit systems are not supported either.
-if (APPLE OR WIN32 OR NOT "cxx_std_17" IN_LIST CMAKE_CXX_COMPILE_FEATURES OR NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
+if (APPLE OR WIN32 OR WASM OR NOT "cxx_std_17" IN_LIST CMAKE_CXX_COMPILE_FEATURES OR NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
   set(ENABLE_LIBOMPTARGET OFF)
 endif()
 
diff --git a/openmp/runtime/CMakeLists.txt b/openmp/runtime/CMakeLists.txt
index 8a913989272c4..80064170db193 100644
--- a/openmp/runtime/CMakeLists.txt
+++ b/openmp/runtime/CMakeLists.txt
@@ -30,7 +30,7 @@ if(${OPENMP_STANDALONE_BUILD})
   # If adding a new architecture, take a look at cmake/LibompGetArchitecture.cmake
   libomp_get_architecture(LIBOMP_DETECTED_ARCH)
   set(LIBOMP_ARCH ${LIBOMP_DETECTED_ARCH} CACHE STRING
-    "The architecture to build for (x86_64/i386/arm/ppc64/ppc64le/aarch64/mic/mips/mips64/riscv64/loongarch64/ve/s390x).")
+    "The architecture to build for (x86_64/i386/arm/ppc64/ppc64le/aarch64/mic/mips/mips64/riscv64/loongarch64/ve/s390x/wasm32).")
   # Should assertions be enabled?  They are on by default.
   set(LIBOMP_ENABLE_ASSERTIONS TRUE CACHE BOOL
     "enable assertions?")
@@ -67,6 +67,8 @@ else() # Part of LLVM build
     set(LIBOMP_ARCH ve)
   elseif(LIBOMP_NATIVE_ARCH MATCHES "s390x")
     set(LIBOMP_ARCH s390x)
+  elseif(LIBOMP_NATIVE_ARCH MATCHES "wasm")
+    set(LIBOMP_ARCH wasm32)
   else()
     # last ditch effort
     libomp_get_architecture(LIBOMP_ARCH)
@@ -87,7 +89,7 @@ if(LIBOMP_ARCH STREQUAL "aarch64")
   endif()
 endif()
 
-libomp_check_variable(LIBOMP_ARCH 32e x86_64 32 i386 arm ppc64 ppc64le aarch64 aarch64_a64fx mic mips mips64 riscv64 loongarch64 ve s390x)
+libomp_check_variable(LIBOMP_ARCH 32e x86_64 32 i386 arm ppc64 ppc64le aarch64 aarch64_a64fx mic mips mips64 riscv64 loongarch64 ve s390x wasm32)
 
 set(LIBOMP_LIB_TYPE normal CACHE STRING
   "Performance,Profiling,Stubs library (normal/profile/stubs)")
@@ -168,6 +170,7 @@ set(RISCV64 FALSE)
 set(LOONGARCH64 FALSE)
 set(VE FALSE)
 set(S390X FALSE)
+set(WASM FALSE)
 if("${LIBOMP_ARCH}" STREQUAL "i386" OR "${LIBOMP_ARCH}" STREQUAL "32")    # IA-32 architecture
   set(IA32 TRUE)
 elseif("${LIBOMP_ARCH}" STREQUAL "x86_64" OR "${LIBOMP_ARCH}" STREQUAL "32e") # Intel(R) 64 architecture
@@ -198,6 +201,8 @@ elseif("${LIBOMP_ARCH}" STREQUAL "ve") # VE architecture
     set(VE TRUE)
 elseif("${LIBOMP_ARCH}" STREQUAL "s390x") # S390x (Z) architecture
     set(S390X TRUE)
+elseif("${LIBOMP_ARCH}" STREQUAL "wasm32") # WebAssembly architecture
+    set(WASM TRUE)
 endif()
 
 # Set some flags based on build_type
@@ -306,6 +311,11 @@ endif()
 set(LIBOMP_ENABLE_SHARED TRUE CACHE BOOL
   "Shared library instead of static library?")
 
+if(WASM)
+  libomp_warning_say("The WebAssembly build currently only supports static libraries; forcing LIBOMP_ENABLE_SHARED to false")
+  set(LIBOMP_ENABLE_SHARED FALSE)
+endif()
+
 if(WIN32 AND NOT LIBOMP_ENABLE_SHARED)
   libomp_error_say("Static libraries requested but not available on Windows")
 endif()
diff --git a/openmp/runtime/cmake/LibompGetArchitecture.cmake b/openmp/runtime/cmake/LibompGetArchitecture.cmake
index 9d4f08b92de50..cd85267020bd6 100644
--- a/openmp/runtime/cmake/LibompGetArchitecture.cmake
+++ b/openmp/runtime/cmake/LibompGetArchitecture.cmake
@@ -53,6 +53,8 @@ function(libomp_get_architecture return_arch)
       #error ARCHITECTURE=ve
     #elif defined(__s390x__)
       #error ARCHITECTURE=s390x
+    #elif defined(__wasm32__)
+      #error ARCHITECTURE=wasm32
     #else
       #error ARCHITECTURE=UnknownArchitecture
     #endif
diff --git a/openmp/runtime/cmake/config-ix.cmake b/openmp/runtime/cmake/config-ix.cmake
index d54d350816926..90b9af4cd3829 100644
--- a/openmp/runtime/cmake/config-ix.cmake
+++ b/openmp/runtime/cmake/config-ix.cmake
@@ -150,15 +150,20 @@ if(CMAKE_C_COMPILER_ID STREQUAL "Intel" OR CMAKE_C_COMPILER_ID STREQUAL "IntelLL
   check_library_exists(irc_pic _intel_fast_memcpy "" LIBOMP_HAVE_IRC_PIC_LIBRARY)
 endif()
 
-# Checking Threading requirements
-find_package(Threads REQUIRED)
-if(WIN32)
-  if(NOT CMAKE_USE_WIN32_THREADS_INIT)
-    libomp_error_say("Need Win32 thread interface on Windows.")
-  endif()
-else()
-  if(NOT CMAKE_USE_PTHREADS_INIT)
-    libomp_error_say("Need pthread interface on Unix-like systems.")
+# Checking threading requirements. Note that compiling to WebAssembly threads
+# with either the Emscripten or wasi-threads flavor ends up using the pthreads
+# interface in a WebAssembly-compiled libc; CMake does not yet know how to
+# detect this.
+if (NOT WASM)
+  find_package(Threads REQUIRED)
+  if(WIN32)
+    if(NOT CMAKE_USE_WIN32_THREADS_INIT)
+      libomp_error_say("Need Win32 thread interface on Windows.")
+    endif()
+  else()
+    if(NOT CMAKE_USE_PTHREADS_INIT)
+      libomp_error_say("Need pthread interface on Unix-like systems.")
+    endif()
   endif()
 endif()
 
diff --git a/openmp/runtime/src/kmp.h b/openmp/runtime/src/kmp.h
index d34adf7cbf8af..3dbf8c71c48d3 100644
--- a/openmp/runtime/src/kmp.h
+++ b/openmp/runtime/src/kmp.h
@@ -63,7 +63,15 @@
 #undef KMP_CANCEL_THREADS
 #endif
 
+// Some WASI targets (e.g., wasm32-wasi-threads) do not support thread
+// cancellation.
+#if KMP_OS_WASI
+#undef KMP_CANCEL_THREADS
+#endif
+
+#if !KMP_OS_WASI
 #include <signal.h>
+#endif
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -124,7 +132,7 @@ class kmp_stats_list;
 #endif
 #include "kmp_i18n.h"
 
-#define KMP_HANDLE_SIGNALS (KMP_OS_UNIX || KMP_OS_WINDOWS)
+#define KMP_HANDLE_SIGNALS ((KMP_OS_UNIX && !KMP_OS_WASI) || KMP_OS_WINDOWS)
 
 #include "kmp_wrapper_malloc.h"
 #if KMP_OS_UNIX
@@ -601,7 +609,9 @@ typedef int PACKED_REDUCTION_METHOD_T;
 #endif
 
 #if KMP_OS_UNIX
+#if !KMP_OS_WASI
 #include <dlfcn.h>
+#endif
 #include <pthread.h>
 #endif
 
@@ -1340,6 +1350,10 @@ extern kmp_uint64 __kmp_now_nsec();
 /* TODO: tune for KMP_OS_SOLARIS */
 #define KMP_INIT_WAIT 1024U /* initial number of spin-tests   */
 #define KMP_NEXT_WAIT 512U /* susequent number of spin-tests */
+#elif KMP_OS_WASI
+/* TODO: tune for KMP_OS_WASI */
+#define KMP_INIT_WAIT 1024U /* initial number of spin-tests   */
+#define KMP_NEXT_WAIT 512U /* susequent number of spin-tests */
 #endif
 
 #if KMP_ARCH_X86 || KMP_ARCH_X86_64
diff --git a/openmp/runtime/src/kmp_ftn_entry.h b/openmp/runtime/src/kmp_ftn_entry.h
index ad19079cb6509..d54c5bfd10fe9 100644
--- a/openmp/runtime/src/kmp_ftn_entry.h
+++ b/openmp/runtime/src/kmp_ftn_entry.h
@@ -593,7 +593,7 @@ int FTN_STDCALL KMP_EXPAND_NAME(FTN_GET_THREAD_NUM)(void) {
     return 0;
   }
   --gtid; // We keep (gtid+1) in TLS
-#elif KMP_OS_LINUX
+#elif KMP_OS_LINUX || KMP_OS_WASI
 #ifdef KMP_TDATA_GTID
   if (__kmp_gtid_mode >= 3) {
     if ((gtid = __kmp_gtid) == KMP_GTID_DNE) {
@@ -1043,7 +1043,7 @@ void FTN_STDCALL KMP_EXPAND_NAME(FTN_SET_DEFAULT_DEVICE)(int KMP_DEREF arg) {
 int FTN_STDCALL KMP_EXPAND_NAME(FTN_GET_NUM_DEVICES)(void)
     KMP_WEAK_ATTRIBUTE_EXTERNAL;
 int FTN_STDCALL KMP_EXPAND_NAME(FTN_GET_NUM_DEVICES)(void) {
-#if KMP_MIC || KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_MIC || KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return 0;
 #else
   int (*fptr)();
@@ -1558,7 +1558,7 @@ typedef void *omp_interop_t;
 
 // libomptarget, if loaded, provides this function
 int FTN_STDCALL FTN_GET_NUM_INTEROP_PROPERTIES(const omp_interop_t interop) {
-#if KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return 0;
 #else
   int (*fptr)(const omp_interop_t);
@@ -1573,7 +1573,7 @@ int FTN_STDCALL FTN_GET_NUM_INTEROP_PROPERTIES(const omp_interop_t interop) {
 intptr_t FTN_STDCALL FTN_GET_INTEROP_INT(const omp_interop_t interop,
                                          omp_interop_property_t property_id,
                                          int *err) {
-#if KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return 0;
 #else
   intptr_t (*fptr)(const omp_interop_t, omp_interop_property_t, int *);
@@ -1587,7 +1587,7 @@ intptr_t FTN_STDCALL FTN_GET_INTEROP_INT(const omp_interop_t interop,
 void *FTN_STDCALL FTN_GET_INTEROP_PTR(const omp_interop_t interop,
                                       omp_interop_property_t property_id,
                                       int *err) {
-#if KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return nullptr;
 #else
   void *(*fptr)(const omp_interop_t, omp_interop_property_t, int *);
@@ -1601,7 +1601,7 @@ void *FTN_STDCALL FTN_GET_INTEROP_PTR(const omp_interop_t interop,
 const char *FTN_STDCALL FTN_GET_INTEROP_STR(const omp_interop_t interop,
                                             omp_interop_property_t property_id,
                                             int *err) {
-#if KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return nullptr;
 #else
   const char *(*fptr)(const omp_interop_t, omp_interop_property_t, int *);
@@ -1614,7 +1614,7 @@ const char *FTN_STDCALL FTN_GET_INTEROP_STR(const omp_interop_t interop,
 // libomptarget, if loaded, provides this function
 const char *FTN_STDCALL FTN_GET_INTEROP_NAME(
     const omp_interop_t interop, omp_interop_property_t property_id) {
-#if KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return nullptr;
 #else
   const char *(*fptr)(const omp_interop_t, omp_interop_property_t);
@@ -1627,7 +1627,7 @@ const char *FTN_STDCALL FTN_GET_INTEROP_NAME(
 // libomptarget, if loaded, provides this function
 const char *FTN_STDCALL FTN_GET_INTEROP_TYPE_DESC(
     const omp_interop_t interop, omp_interop_property_t property_id) {
-#if KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return nullptr;
 #else
   const char *(*fptr)(const omp_interop_t, omp_interop_property_t);
@@ -1640,7 +1640,7 @@ const char *FTN_STDCALL FTN_GET_INTEROP_TYPE_DESC(
 // libomptarget, if loaded, provides this function
 const char *FTN_STDCALL FTN_GET_INTEROP_RC_DESC(
     const omp_interop_t interop, omp_interop_property_t property_id) {
-#if KMP_OS_DARWIN || defined(KMP_STUB)
+#if KMP_OS_DARWIN || KMP_OS_WASI || defined(KMP_STUB)
   return nullptr;
 #else
   const char *(*fptr)(const omp_interop_t, omp_interop_property_t);
diff --git a/openmp/runtime/src/kmp_gsupport.cpp b/openmp/runtime/src/kmp_gsupport.cpp
index d77d4809a7e95..dc843f78dc697 100644
--- a/openmp/runtime/src/kmp_gsupport.cpp
+++ b/openmp/runtime/src/kmp_gsupport.cpp
@@ -356,7 +356,7 @@ void KMP_EXPAND_NAME(KMP_API_NAME_GOMP_ORDERED_END)(void) {
 // They come in two flavors: 64-bit unsigned, and either 32-bit signed
 // (IA-32 architecture) or 64-bit signed (Intel(R) 64).
 
-#if KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_MIPS
+#if KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_MIPS || KMP_ARCH_WASM
 #define KMP_DISPATCH_INIT __kmp_aux_dispatch_init_4
 #define KMP_DISPATCH_FINI_CHUNK __kmp_aux_dispatch_fini_chunk_4
 #define KMP_DISPATCH_NEXT __kmpc_dispatch_next_4
diff --git a/openmp/runtime/src/kmp_os.h b/openmp/runtime/src/kmp_os.h
index beb8d0197ddf5..4ffe9f2d8c953 100644
--- a/openmp/runtime/src/kmp_os.h
+++ b/openmp/runtime/src/kmp_os.h
@@ -75,7 +75,7 @@
 #error Unknown compiler
 #endif
 
-#if (KMP_OS_LINUX || KMP_OS_WINDOWS || KMP_OS_FREEBSD)
+#if (KMP_OS_LINUX || KMP_OS_WINDOWS || KMP_OS_FREEBSD) && !KMP_OS_WASI
 #define KMP_AFFINITY_SUPPORTED 1
 #if KMP_OS_WINDOWS && KMP_ARCH_X86_64
 #define KMP_GROUP_AFFINITY 1
@@ -176,7 +176,7 @@ typedef unsigned long long kmp_uint64;
 #define KMP_UINT64_SPEC "llu"
 #endif /* KMP_OS_UNIX */
 
-#if KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_MIPS
+#if KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_MIPS || KMP_ARCH_WASM
 #define KMP_SIZE_T_SPEC KMP_UINT32_SPEC
 #elif KMP_ARCH_X86_64 || KMP_ARCH_PPC64 || KMP_ARCH_AARCH64 ||                 \
     KMP_ARCH_MIPS64 || KMP_ARCH_RISCV64 || KMP_ARCH_LOONGARCH64 ||             \
@@ -186,7 +186,7 @@ typedef unsigned long long kmp_uint64;
 #error "Can't determine size_t printf format specifier."
 #endif
 
-#if KMP_ARCH_X86 || KMP_ARCH_ARM
+#if KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_WASM
 #define KMP_SIZE_T_MAX (0xFFFFFFFF)
 #else
 #define KMP_SIZE_T_MAX (0xFFFFFFFFFFFFFFFF)
@@ -215,8 +215,8 @@ typedef kmp_uint32 kmp_uint;
 #define KMP_INT_MIN ((kmp_int32)0x80000000)
 
 // stdarg handling
-#if (KMP_ARCH_ARM || KMP_ARCH_X86_64 || KMP_ARCH_AARCH64) &&                   \
-    (KMP_OS_FREEBSD || KMP_OS_LINUX)
+#if (KMP_ARCH_ARM || KMP_ARCH_X86_64 || KMP_ARCH_AARCH64 || KMP_ARCH_WASM) &&  \
+    (KMP_OS_FREEBSD || KMP_OS_LINUX || KMP_OS_WASI)
 typedef va_list *kmp_va_list;
 #define kmp_va_deref(ap) (*(ap))
 #define kmp_va_addr_of(ap) (&(ap))
@@ -1146,7 +1146,7 @@ extern kmp_real64 __kmp_xchg_real64(volatile kmp_real64 *p, kmp_real64 v);
   KMP_COMPARE_AND_STORE_REL64((volatile kmp_int64 *)(volatile void *)&(a),     \
                               (kmp_int64)(b), (kmp_int64)(c))
 
-#if KMP_ARCH_X86 || KMP_ARCH_MIPS
+#if KMP_ARCH_X86 || KMP_ARCH_MIPS || KMP_ARCH_WASM
 // What about ARM?
 #define TCR_PTR(a) ((void *)TCR_4(a))
 #define TCW_PTR(a, b) TCW_4((a), (b))
@@ -1288,6 +1288,9 @@ bool __kmp_atomic_compare_store_rel(std::atomic<T> *p, T expected, T desired) {
 extern void *__kmp_lookup_symbol(const char *name, bool next = false);
 #define KMP_DLSYM(name) __kmp_lookup_symbol(name)
 #define KMP_DLSYM_NEXT(name) __kmp_lookup_symbol(name, true)
+#elif KMP_OS_WASI
+#define KMP_DLSYM(name) nullptr
+#define KMP_DLSYM_NEXT(name) nullptr
 #else
 #define KMP_DLSYM(name) dlsym(RTLD_DEFAULT, name)
 #define KMP_DLSYM_NEXT(name) dlsym(RTLD_NEXT, name)
diff --git a/openmp/runtime/src/kmp_platform.h b/openmp/runtime/src/kmp_platform.h
index b7972c7248dd5..45f411b9c2194 100644
--- a/openmp/runtime/src/kmp_platform.h
+++ b/openmp/runtime/src/kmp_platform.h
@@ -24,6 +24,7 @@
 #define KMP_OS_WINDOWS 0
 #define KMP_OS_HURD 0
 #define KMP_OS_SOLARIS 0
+#define KMP_OS_WASI 0
 #define KMP_OS_UNIX 0 /* disjunction of KMP_OS_LINUX, KMP_OS_DARWIN etc. */
 
 #ifdef _WIN32
@@ -76,14 +77,20 @@
 #define KMP_OS_SOLARIS 1
 #endif
 
+#if (defined __wasi__) || (defined __EMSCRIPTEN__)
+#undef KMP_OS_WASI
+#define KMP_OS_WASI 1
+#endif
+
 #if (1 != KMP_OS_LINUX + KMP_OS_DRAGONFLY + KMP_OS_FREEBSD + KMP_OS_NETBSD +   \
               KMP_OS_OPENBSD + KMP_OS_DARWIN + KMP_OS_WINDOWS + KMP_OS_HURD +  \
-              KMP_OS_SOLARIS)
+              KMP_OS_SOLARIS + KMP_OS_WASI)
 #error Unknown OS
 #endif
 
 #if KMP_OS_LINUX || KMP_OS_DRAGONFLY || KMP_OS_FREEBSD || KMP_OS_NETBSD ||     \
-    KMP_OS_OPENBSD || KMP_OS_DARWIN || KMP_OS_HURD || KMP_OS_SOLARIS
+    KMP_OS_OPENBSD || KMP_OS_DARWIN || KMP_OS_HURD || KMP_OS_SOLARIS ||        \
+    KMP_OS_WASI
 #undef KMP_OS_UNIX
 #define KMP_OS_UNIX 1
 #endif
@@ -196,6 +203,10 @@
 #define KMP_ARCH_ARM 1
 #endif
 
+#if defined(__wasm32__)
+#define KMP_ARCH_WASM 1
+#endif
+
 #if defined(__MIC__) || defined(__MIC2__)
 #define KMP_MIC 1
 #if __MIC2__ || __KNC__
@@ -212,7 +223,8 @@
 #endif
 
 /* Specify 32 bit architectures here */
-#define KMP_32_BIT_ARCH (KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_MIPS)
+#define KMP_32_BIT_ARCH                                                        \
+  (KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_MIPS || KMP_ARCH_WASM)
 
 // Platforms which support Intel(R) Many Integrated Core Architecture
 #define KMP_MIC_SUPPORTED                                                      \
@@ -222,7 +234,7 @@
 #if (1 != KMP_ARCH_X86 + KMP_ARCH_X86_64 + KMP_ARCH_ARM + KMP_ARCH_PPC64 +     \
               KMP_ARCH_AARCH64 + KMP_ARCH_MIPS + KMP_ARCH_MIPS64 +             \
               KMP_ARCH_RISCV64 + KMP_ARCH_LOONGARCH64 + KMP_ARCH_VE +          \
-              KMP_ARCH_S390X)
+              KMP_ARCH_S390X + KMP_ARCH_WASM)
 #error Unknown or unsupported architecture
 #endif
 
diff --git a/openmp/runtime/src/kmp_runtime.cpp b/openmp/runtime/src/kmp_runtime.cpp
index 25136691bc72d..7d2e7a99ade43 100644
--- a/openmp/runtime/src/kmp_runtime.cpp
+++ b/openmp/runtime/src/kmp_runtime.cpp
@@ -47,8 +47,9 @@ static char *ProfileTraceFile = nullptr;
 #include <process.h>
 #endif
 
-#if KMP_OS_WINDOWS
-// windows does not need include files as it doesn't use shared memory
+#ifndef KMP_USE_SHM
+// Windows and WASI do not need these include files as they don't use shared
+// memory.
 #else
 #include <sys/mman.h>
 #include <sys/stat.h>
@@ -446,26 +447,26 @@ void __kmp_abort_process() {
     __kmp_dump_debug_buffer();
   }
 
-  if (KMP_OS_WINDOWS) {
-    // Let other threads know of abnormal termination and prevent deadlock
-    // if abort happened during library initialization or shutdown
-    __kmp_global.g.g_abort = SIGABRT;
-
-    /* On Windows* OS by default abort() causes pop-up error box, which stalls
-       nightly testing. Unfortunately, we cannot reliably suppress pop-up error
-       boxes. _set_abort_behavior() works well, but this function is not
-       available in VS7 (this is not problem for DLL, but it is a problem for
-       static OpenMP RTL). SetErrorMode (and so, timelimit utility) does not
-       help, at least in some versions of MS C RTL.
-
-       It seems following sequence is the only way to simulate abort() and
-       avoid pop-up error box. */
-    raise(SIGABRT);
-    _exit(3); // Just in case, if signal ignored, exit anyway.
-  } else {
-    __kmp_unregister_library();
-    abort();
-  }
+#if KMP_OS_WINDOWS
+  // Let other threads know of abnormal termination and prevent deadlock
+  // if abort happened during library initialization or shutdown
+  __kmp_global.g.g_abort = SIGABRT;
+
+  /* On Windows* OS by default abort() causes pop-up error box, which stalls
+     nightly testing. Unfortunately, we cannot reliably suppress pop-up error
+     boxes. _set_abort_behavior() works well, but this function is not
+     available in VS7 (this is not problem for DLL, but it is a problem for
+     static OpenMP RTL). SetErrorMode (and so, timelimit utility) does not
+     help, at least in some versions of MS C RTL.
+
+     It seems following sequence is the only way to simulate abort() and
+     avoid pop-up error box. */
+  raise(SIGABRT);
+  _exit(3); // Just in case, if signal ignored, exit anyway.
+#else
+  __kmp_unregister_library();
+  abort();
+#endif
 
   __kmp_infinite_loop();
   __kmp_release_bootstrap_lock(&__kmp_exit_lock);
@@ -8895,11 +8896,11 @@ __kmp_determine_reduction_method(
 
 #if KMP_ARCH_X86_64 || KMP_ARCH_PPC64 || KMP_ARCH_AARCH64 ||                   \
     KMP_ARCH_MIPS64 || KMP_ARCH_RISCV64 || KMP_ARCH_LOONGARCH64 ||             \
-    KMP_ARCH_VE || KMP_ARCH_S390X
+    KMP_ARCH_VE || KMP_ARCH_S390X || KMP_ARCH_WASM
 
 #if KMP_OS_LINUX || KMP_OS_DRAGONFLY || KMP_OS_FREEBSD || KMP_OS_NETBSD ||     \
     KMP_OS_OPENBSD || KMP_OS_WINDOWS || KMP_OS_DARWIN || KMP_OS_HURD ||        \
-    KMP_OS_SOLARIS
+    KMP_OS_SOLARIS || KMP_OS_WASI
 
     int teamsize_cutoff = 4;
 
@@ -8924,12 +8925,14 @@ __kmp_determine_reduction_method(
 #error "Unknown or unsupported OS"
 #endif // KMP_OS_LINUX || KMP_OS_DRAGONFLY || KMP_OS_FREEBSD || KMP_OS_NETBSD ||
        // KMP_OS_OPENBSD || KMP_OS_WINDOWS || KMP_OS_DARWIN || KMP_OS_HURD ||
-       // KMP_OS_SOLARIS
+       // KMP_OS_SOLARIS || KMP_OS_WASI
 
-#elif KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_AARCH || KMP_ARCH_MIPS
+#elif KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_AARCH || KMP_ARCH_MIPS ||       \
+    KMP_ARCH_WASM
 
 #if KMP_OS_LINUX || KMP_OS_DRAGONFLY || KMP_OS_FREEBSD || KMP_OS_NETBSD ||     \
-    KMP_OS_OPENBSD || KMP_OS_WINDOWS || KMP_OS_HURD || KMP_OS_SOLARIS
+    KMP_OS_OPENBSD || KMP_OS_WINDOWS || KMP_OS_HURD || KMP_OS_SOLARIS ||       \
+    KMP_OS_WASI
 
     // basic tuning
 
diff --git a/openmp/runtime/src/kmp_utility.cpp b/openmp/runtime/src/kmp_utility.cpp
index 3174bbb7a5b75..f901eaca92f4d 100644
--- a/openmp/runtime/src/kmp_utility.cpp
+++ b/openmp/runtime/src/kmp_utility.cpp
@@ -294,6 +294,8 @@ void __kmp_expand_host_name(char *buffer, size_t size) {
     if (!GetComputerNameA(buffer, &s))
       KMP_STRCPY_S(buffer, size, unknown);
   }
+#elif KMP_OS_WASI
+  KMP_STRCPY_S(buffer, size, unknown);
 #else
   buffer[size - 2] = 0;
   if (gethostname(buffer, size) || buffer[size - 2] != 0)
diff --git a/openmp/runtime/src/z_Linux_asm.S b/openmp/runtime/src/z_Linux_asm.S
index a72705528d416..14987c298fa5f 100644
--- a/openmp/runtime/src/z_Linux_asm.S
+++ b/openmp/runtime/src/z_Linux_asm.S
@@ -2441,7 +2441,27 @@ KMP_PREFIX_UNDERSCORE(__kmp_unnamed_critical_addr):
 #if KMP_OS_LINUX
 # if KMP_ARCH_ARM || KMP_ARCH_AARCH64
 .section .note.GNU-stack,"",%progbits
-# else
+# elif !KMP_ARCH_WASM
 .section .note.GNU-stack,"",@progbits
 # endif
 #endif
+
+#if KMP_ARCH_WASM
+.data
+.global .gomp_critical_user_
+.global .gomp_critical_user_.var
+.global .gomp_critical_user_.reduction.var
+.global __kmp_unnamed_critical_addr
+.gomp_critical_user_:
+.zero 4
+.size .gomp_critical_user_, 4
+.gomp_critical_user_.var:
+.zero 4
+.size .gomp_critical_user_.var, 4
+.gomp_critical_user_.reduction.var:
+.zero 4
+.size .gomp_critical_user_.reduction.var, 4
+__kmp_unnamed_critical_addr:
+    .4byte .gomp_critical_user_
+    .size __kmp_unnamed_critical_addr, 4
+#endif
diff --git a/openmp/runtime/src/z_Linux_util.cpp b/openmp/runtime/src/z_Linux_util.cpp
index 72da0f79865df..a1f64b067b1f5 100644
--- a/openmp/runtime/src/z_Linux_util.cpp
+++ b/openmp/runtime/src/z_Linux_util.cpp
@@ -277,7 +277,7 @@ int __kmp_futex_determine_capable() {
 
 #endif // KMP_USE_FUTEX
 
-#if (KMP_ARCH_X86 || KMP_ARCH_X86_64) && (!KMP_ASM_INTRINS)
+#if (KMP_ARCH_X86 || KMP_ARCH_X86_64 || KMP_ARCH_WASM) && (!KMP_ASM_INTRINS)
 /* Only 32-bit "add-exchange" instruction on IA-32 architecture causes us to
    use compare_and_store for these routines */
 
@@ -337,7 +337,7 @@ kmp_uint32 __kmp_test_then_and32(volatile kmp_uint32 *p, kmp_uint32 d) {
   return old_value;
 }
 
-#if KMP_ARCH_X86
+#if KMP_ARCH_X86 || KMP_ARCH_WASM
 kmp_int8 __kmp_test_then_add8(volatile kmp_int8 *p, kmp_int8 d) {
   kmp_int8 old_value, new_value;
 
@@ -985,7 +985,11 @@ void __kmp_create_monitor(kmp_info_t *th) {
 #endif // KMP_USE_MONITOR
 
 void __kmp_exit_thread(int exit_status) {
+#if KMP_OS_WASI
+// TODO: the wasm32-wasi-threads target does not yet support pthread_exit.
+#else
   pthread_exit((void *)(intptr_t)exit_status);
+#endif
 } // __kmp_exit_thread
 
 #if KMP_USE_MONITOR
@@ -1330,9 +1334,11 @@ static void __kmp_atfork_child(void) {
 
 void __kmp_register_atfork(void) {
   if (__kmp_need_register_atfork) {
+#if !KMP_OS_WASI
     int status = pthread_atfork(__kmp_atfork_prepare, __kmp_atfork_parent,
                                 __kmp_atfork_child);
     KMP_CHECK_SYSFAIL("pthread_atfork", status);
+#endif
     __kmp_need_register_atfork = FALSE;
   }
 }
@@ -1774,6 +1780,7 @@ int __kmp_read_system_info(struct kmp_sys_info *info) {
   status = getrusage(RUSAGE_SELF, &r_usage);
   KMP_CHECK_SYSFAIL_ERRNO("getrusage", status);
 
+#if !KMP_OS_WASI
   // The maximum resident set size utilized (in kilobytes)
   info->maxrss = r_usage.ru_maxrss;
   // The number of page faults serviced without any I/O
@@ -1790,6 +1797,7 @@ int __kmp_read_system_info(struct kmp_sys_info *info) {
   info->nvcsw = r_usage.ru_nvcsw;
   // The number of times a context switch was forced
   info->nivcsw = r_usage.ru_nivcsw;
+#endif
 
   return (status != 0);
 }
@@ -1824,7 +1832,7 @@ static int __kmp_get_xproc(void) {
   __kmp_type_convert(sysconf(_SC_NPROCESSORS_CONF), &(r));
 
 #elif KMP_OS_DRAGONFLY || KMP_OS_FREEBSD || KMP_OS_NETBSD || KMP_OS_OPENBSD || \
-    KMP_OS_HURD || KMP_OS_SOLARIS
+    KMP_OS_HURD || KMP_OS_SOLARIS || KMP_OS_WASI
 
   __kmp_type_convert(sysconf(_SC_NPROCESSORS_ONLN), &(r));
 
@@ -2200,6 +2208,8 @@ int __kmp_is_address_mapped(void *addr) {
     }
     kiv.kve_start += 1;
   }
+#elif KMP_OS_WASI
+  found = (int)addr < (__builtin_wasm_memory_size(0) * PAGESIZE);
 #elif KMP_OS_DRAGONFLY || KMP_OS_SOLARIS
 
   // FIXME(DragonFly, Solaris): Implement this