diff --git a/clang/lib/CIR/CodeGen/CIRGenCUDANV.cpp b/clang/lib/CIR/CodeGen/CIRGenCUDANV.cpp
index 2b64997de866..4377d27d438d 100644
--- a/clang/lib/CIR/CodeGen/CIRGenCUDANV.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenCUDANV.cpp
@@ -161,12 +161,18 @@ void CIRGenNVCUDARuntime::emitDeviceStubBodyNew(CIRGenFunction &cgf,
 
   // The default stream is usually stream 0 (the legacy default stream).
   // For per-thread default stream, we need a different LaunchKernel function.
+  std::string kernelLaunchAPI = "LaunchKernel";
   if (cgm.getLangOpts().GPUDefaultStream ==
-      LangOptions::GPUDefaultStreamKind::PerThread)
-    llvm_unreachable("NYI");
+      LangOptions::GPUDefaultStreamKind::PerThread) {
+    if (cgf.getLangOpts().HIP)
+      kernelLaunchAPI = kernelLaunchAPI + "_spt";
+    else if (cgf.getLangOpts().CUDA)
+      kernelLaunchAPI = kernelLaunchAPI + "_ptsz";
+  }
 
-  std::string launchAPI = addPrefixToName("LaunchKernel");
-  const IdentifierInfo &launchII = cgm.getASTContext().Idents.get(launchAPI);
+  std::string launchKernelName = addPrefixToName(kernelLaunchAPI);
+  const IdentifierInfo &launchII =
+      cgm.getASTContext().Idents.get(launchKernelName);
   FunctionDecl *launchFD = nullptr;
   for (auto *result : dc->lookup(&launchII)) {
     if (FunctionDecl *fd = dyn_cast<FunctionDecl>(result))
@@ -175,7 +181,7 @@ void CIRGenNVCUDARuntime::emitDeviceStubBodyNew(CIRGenFunction &cgf,
 
   if (launchFD == nullptr) {
     cgm.Error(cgf.CurFuncDecl->getLocation(),
-              "Can't find declaration for " + launchAPI);
+              "Can't find declaration for " + launchKernelName);
     return;
   }
 
@@ -256,8 +262,8 @@ void CIRGenNVCUDARuntime::emitDeviceStubBodyNew(CIRGenFunction &cgf,
                  launchFD->getParamDecl(5)->getType());
 
   mlir::Type launchTy = cgm.getTypes().convertType(launchFD->getType());
-  mlir::Operation *launchFn =
-      cgm.createRuntimeFunction(cast<cir::FuncType>(launchTy), launchAPI);
+  mlir::Operation *launchFn = cgm.createRuntimeFunction(
+      cast<cir::FuncType>(launchTy), launchKernelName);
   const auto &callInfo = cgm.getTypes().arrangeFunctionDeclaration(launchFD);
   cgf.emitCall(callInfo, CIRGenCallee::forDirect(launchFn), ReturnValueSlot(),
                launchArgs);
diff --git a/clang/test/CIR/CodeGen/CUDA/simple.cu b/clang/test/CIR/CodeGen/CUDA/simple.cu
index 2d4f12da39e0..1c55a89a0670 100644
--- a/clang/test/CIR/CodeGen/CUDA/simple.cu
+++ b/clang/test/CIR/CodeGen/CUDA/simple.cu
@@ -30,6 +30,26 @@
 // RUN:            %s -o %t.ll
 // RUN: FileCheck --check-prefix=OGCG-DEVICE --input-file=%t.ll %s
 
+// Per Thread Stream test cases:
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir \
+// RUN:            -x cuda -emit-cir -target-sdk-version=12.3 \
+// RUN: -fgpu-default-stream=per-thread -DCUDA_API_PER_THREAD_DEFAULT_STREAM \
+// RUN:            %s -o %t.cir
+// RUN: FileCheck --check-prefixes=CIR-HOST-PTH --input-file=%t.cir %s
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir \
+// RUN:            -x cuda -emit-llvm -target-sdk-version=12.3 \
+// RUN: -fgpu-default-stream=per-thread -DCUDA_API_PER_THREAD_DEFAULT_STREAM \
+// RUN:            %s -o %t.ll
+// RUN: FileCheck --check-prefixes=LLVM-HOST-PTH --input-file=%t.ll %s
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu \
+// RUN:            -x cuda -emit-llvm -target-sdk-version=12.3 \
+// RUN: -fgpu-default-stream=per-thread -DCUDA_API_PER_THREAD_DEFAULT_STREAM \
+// RUN:            %s -o %t.ll
+// RUN: FileCheck --check-prefixes=OGCG-HOST-PTH --input-file=%t.ll %s
+
 // Attribute for global_fn
 // CIR-HOST: [[Kernel:#[a-zA-Z_0-9]+]] = {{.*}}#cir.cu.kernel_name<_Z9global_fni>{{.*}}
 
@@ -54,6 +74,7 @@ __global__ void global_fn(int a) {}
 // CIR-HOST: cir.call @__cudaPopCallConfiguration
 // CIR-HOST: cir.get_global @_Z24__device_stub__global_fni
 // CIR-HOST: cir.call @cudaLaunchKernel
+// CIR-HOST-PTH: cir.call @cudaLaunchKernel_ptsz
 
 // LLVM-HOST: void @_Z24__device_stub__global_fni
 // LLVM-HOST: %[[#KernelArgs:]] = alloca [1 x ptr], i64 1, align 16
@@ -61,12 +82,14 @@ __global__ void global_fn(int a) {}
 // LLVM-HOST: %[[#GEP2:]] = getelementptr [1 x ptr], ptr %[[#KernelArgs]], i32 0, i64 0
 // LLVM-HOST: call i32 @__cudaPopCallConfiguration
 // LLVM-HOST: call i32 @cudaLaunchKernel(ptr @_Z24__device_stub__global_fni
+// LLVM-HOST-PTH: call i32 @cudaLaunchKernel_ptsz(ptr @_Z24__device_stub__global_fni
 
 // OGCG-HOST: void @_Z24__device_stub__global_fni
 // OGCG-HOST: %kernel_args = alloca ptr, i64 1, align 16
 // OGCG-HOST: getelementptr ptr, ptr %kernel_args, i32 0
 // OGCG-HOST: call i32 @__cudaPopCallConfiguration
 // OGCG-HOST: call noundef i32 @cudaLaunchKernel(ptr noundef @_Z24__device_stub__global_fni
+// OGCG-HOST-PTH: call noundef i32 @cudaLaunchKernel_ptsz(ptr noundef @_Z24__device_stub__global_fni
 
 
 int main() {
diff --git a/clang/test/CIR/CodeGen/HIP/simple.cpp b/clang/test/CIR/CodeGen/HIP/simple.cpp
index 1f1049856d8d..c1dc08a5abee 100644
--- a/clang/test/CIR/CodeGen/HIP/simple.cpp
+++ b/clang/test/CIR/CodeGen/HIP/simple.cpp
@@ -30,6 +30,26 @@
 // RUN:            -I%S/../Inputs/ -emit-llvm %s -o %t.ll
 // RUN: FileCheck --check-prefix=OGCG-DEVICE --input-file=%t.ll %s
 
+// Per Thread Stream test cases:
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir \
+// RUN:            -fgpu-default-stream=per-thread -DHIP_API_PER_THREAD_DEFAULT_STREAM \
+// RUN:            -x hip -fhip-new-launch-api \
+// RUN:            -I%S/../Inputs/ -emit-cir %s -o %t.cir
+// RUN: FileCheck --check-prefix=CIR-HOST-PTH --input-file=%t.cir %s
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir \
+// RUN:            -fgpu-default-stream=per-thread -DHIP_API_PER_THREAD_DEFAULT_STREAM \
+// RUN:            -x hip -emit-llvm -fhip-new-launch-api \
+// RUN:            -I%S/../Inputs/ %s -o %t.ll
+// RUN: FileCheck --check-prefix=LLVM-HOST-PTH --input-file=%t.ll %s
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu  \
+// RUN:            -fgpu-default-stream=per-thread -DHIP_API_PER_THREAD_DEFAULT_STREAM \
+// RUN:            -x  hip -emit-llvm -fhip-new-launch-api \
+// RUN:            -I%S/../Inputs/ %s -o %t.ll
+// RUN: FileCheck --check-prefix=OGCG-HOST-PTH --input-file=%t.ll %s
+
 
 // Attribute for global_fn
 // CIR-HOST: [[Kernel:#[a-zA-Z_0-9]+]] = {{.*}}#cir.cu.kernel_name<_Z9global_fni>{{.*}}
@@ -54,6 +74,7 @@ __global__ void global_fn(int a) {}
 // CIR-HOST: cir.call @__hipPopCallConfiguration
 // CIR-HOST: cir.get_global @_Z9global_fni : !cir.ptr<!cir.ptr<!cir.func<(!s32i)>>>
 // CIR-HOST: cir.call @hipLaunchKernel
+// CIR-HOST-PTH: cir.call @hipLaunchKernel_spt
 
 // LLVM-HOST: void @_Z24__device_stub__global_fni
 // LLVM-HOST: %[[#KernelArgs:]] = alloca [1 x ptr], i64 1, align 16
@@ -61,12 +82,14 @@ __global__ void global_fn(int a) {}
 // LLVM-HOST: %[[#GEP2:]] = getelementptr [1 x ptr], ptr %[[#KernelArgs]], i32 0, i64 0
 // LLVM-HOST: call i32 @__hipPopCallConfiguration
 // LLVM-HOST: call i32 @hipLaunchKernel(ptr @_Z9global_fni 
+// LLVM-HOST-PTH: call i32 @hipLaunchKernel_spt(ptr @_Z9global_fni 
 //
 // OGCG-HOST: define dso_local void @_Z24__device_stub__global_fni
 // OGCG-HOST: %kernel_args = alloca ptr, i64 1, align 16
 // OGCG-HOST: getelementptr ptr, ptr %kernel_args, i32 0
 // OGCG-HOST: call i32 @__hipPopCallConfiguration
 // OGCG-HOST: %call = call noundef i32 @hipLaunchKernel(ptr noundef @_Z9global_fni
+// OGCG-HOST-PTH: %call = call noundef i32 @hipLaunchKernel_spt(ptr noundef @_Z9global_fni
 
 
 int main() {