diff --git a/clang/test/CIR/CodeGen/X86/avx-builtins.c b/clang/test/CIR/CodeGen/X86/avx-builtins.c
index 6c2617d9486a..ba615ec25807 100644
--- a/clang/test/CIR/CodeGen/X86/avx-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/avx-builtins.c
@@ -18,6 +18,9 @@
 // RUN: %clang_cc1 -x c++ -flax-vector-conversions=none -ffreestanding %s -triple=x86_64-unknown-linux -target-feature +avx -fno-signed-char -fclangir -emit-llvm -o %t.ll -Wall -Werror
 // RUN: FileCheck --check-prefixes=LLVM-CHECK,LLVM-X64 --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/avx-builtins.c, which eventually
+// CIR shall be able to support fully.
+
 #include <immintrin.h>
 
 int test_mm256_extract_epi8(__m256i A) {
diff --git a/clang/test/CIR/CodeGen/X86/bmi-builtins.c b/clang/test/CIR/CodeGen/X86/bmi-builtins.c
index 52d555bcd59f..6e5873bfd339 100644
--- a/clang/test/CIR/CodeGen/X86/bmi-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/bmi-builtins.c
@@ -3,6 +3,9 @@
 // RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -fclangir -emit-llvm -o %t.ll %s
 // RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/bmi-builtins.c, which eventually
+// CIR shall be able to support fully.
+
 #include <immintrin.h>
 
 unsigned short test__tzcnt_u16(unsigned short __X) {
@@ -29,4 +32,4 @@ unsigned long long test__tzcnt_u64(unsigned long long __X) {
   // CIR: {{%.*}} = cir.llvm.intrinsic "cttz" {{%.*}} : (!u64i, !cir.bool) -> !u64i
   // LLVM: i64 @llvm.cttz.i64(i64 %{{.*}}, i1 false)
 }
-#endif
\ No newline at end of file
+#endif
diff --git a/clang/test/CIR/CodeGen/X86/builtins-x86.c b/clang/test/CIR/CodeGen/X86/builtins-x86.c
deleted file mode 100644
index c8d00aaf3bf2..000000000000
--- a/clang/test/CIR/CodeGen/X86/builtins-x86.c
+++ /dev/null
@@ -1,47 +0,0 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux -Wno-implicit-function-declaration -fclangir -emit-cir -o %t.cir %s
-// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
-// RUN: %clang_cc1 -triple x86_64-unknown-linux -Wno-implicit-function-declaration -fclangir -emit-llvm -o %t.ll %s
-// RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s
-
-// This test mimics clang/test/CodeGen/builtins-x86.c, which eventually
-// CIR shall be able to support fully.
-
-void test_mm_clflush(const void* tmp_vCp) {
-  // CIR-LABEL: test_mm_clflush
-  // LLVM-LABEL: test_mm_clflush
-  _mm_clflush(tmp_vCp);
-  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse2.clflush" {{%.*}} : (!cir.ptr<!void>) -> !void
-  // LLVM: call void @llvm.x86.sse2.clflush(ptr {{%.*}})
-}
-
-void test_mm_lfence() {
-  // CIR-LABEL: test_mm_lfence
-  // LLVM-LABEL: test_mm_lfence
-  _mm_lfence();
-  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse2.lfence" : () -> !void
-  // LLVM: call void @llvm.x86.sse2.lfence()
-}
-
-void test_mm_pause() {
-  // CIR-LABEL: test_mm_pause
-  // LLVM-LABEL: test_mm_pause
-  _mm_pause();
-  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse2.pause" : () -> !void
-  // LLVM: call void @llvm.x86.sse2.pause()
-}
-
-void test_mm_mfence() {
-  // CIR-LABEL: test_mm_mfence
-  // LLVM-LABEL: test_mm_mfence
-  _mm_mfence();
-  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse2.mfence" : () -> !void
-  // LLVM: call void @llvm.x86.sse2.mfence()
-}
-
-void test_mm_sfence() {
-  // CIR-LABEL: test_mm_sfence
-  // LLVM-LABEL: test_mm_sfence
-  _mm_sfence();
-  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse.sfence" : () -> !void
-  // LLVM: call void @llvm.x86.sse.sfence()
-}
diff --git a/clang/test/CIR/CodeGen/X86/lzcnt-builtins.c b/clang/test/CIR/CodeGen/X86/lzcnt-builtins.c
index 6055afbf9ba8..384be85f9916 100644
--- a/clang/test/CIR/CodeGen/X86/lzcnt-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/lzcnt-builtins.c
@@ -3,6 +3,9 @@
 // RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -fclangir -emit-llvm -o %t.ll %s
 // RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/lzcnt-builtins.c, which eventually
+// CIR shall be able to support fully.
+
 #include <immintrin.h>
 
 unsigned int test_lzcnt_u32(unsigned int __X)
diff --git a/clang/test/CIR/CodeGen/X86/mmx-builtins.c b/clang/test/CIR/CodeGen/X86/mmx-builtins.c
index 6643ec20201c..3b75c00995b7 100644
--- a/clang/test/CIR/CodeGen/X86/mmx-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/mmx-builtins.c
@@ -8,6 +8,9 @@
 // RUN: %clang_cc1 -x c -flax-vector-conversions=none -ffreestanding %s -triple=x86_64-unknown-linux -target-feature +ssse3 -fno-signed-char -fclangir -emit-llvm -o %t.ll -Wall -Werror
 // RUN: FileCheck --check-prefix=LLVM-CHECK --implicit-check-not=x86mmx --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/mmx-builtins.c, which eventually
+// CIR shall be able to support fully.
+
 #include <immintrin.h>
 
 int test_mm_extract_pi16(__m64 a) {
diff --git a/clang/test/CIR/CodeGen/X86/pause.c b/clang/test/CIR/CodeGen/X86/pause.c
new file mode 100644
index 000000000000..67a0d6770c51
--- /dev/null
+++ b/clang/test/CIR/CodeGen/X86/pause.c
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -target-feature +sse2 -fclangir -emit-cir -o %t.cir %s
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -target-feature +sse2 -fclangir -emit-llvm -o %t.ll %s
+// RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s
+
+// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -target-feature -sse2 -fclangir -emit-cir -o %t.cir %s
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -target-feature -sse2 -fclangir -emit-llvm -o %t.ll %s
+// RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s
+
+// This test mimics clang/test/CodeGen/X86/pause.c, which eventually
+// CIR shall be able to support fully.
+
+#include <x86intrin.h>
+
+void test_mm_pause(void) {
+  // CIR-LABEL: test_mm_pause
+  // LLVM-LABEL: test_mm_pause
+  _mm_pause();
+  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse2.pause" : () -> !void
+  // LLVM: call void @llvm.x86.sse2.pause()
+}
diff --git a/clang/test/CIR/CodeGen/X86/rd-builtins.c b/clang/test/CIR/CodeGen/X86/rd-builtins.c
index 8f8902199b10..2c279ceba24c 100644
--- a/clang/test/CIR/CodeGen/X86/rd-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/rd-builtins.c
@@ -8,7 +8,7 @@
 
 #include <x86intrin.h>
 
-unsigned long long test_rdtsc() {
+int test_rdtsc(void) {
   // CIR-LABEL: @test_rdtsc
   // LLVM-LABEL: @test_rdtsc
   return __rdtsc();
@@ -32,4 +32,3 @@ unsigned long long test_rdtscp(unsigned int *a) {
   // LLVM: store i32 [[TSC_AUX]], ptr %{{.*}}
   // LLVM: [[TSC:%.*]] = extractvalue { i64, i32 } [[RDTSCP]], 0
 }
-
diff --git a/clang/test/CIR/CodeGen/X86/sse-builtins.c b/clang/test/CIR/CodeGen/X86/sse-builtins.c
index 08e805bce334..8b2c8fd1eb38 100644
--- a/clang/test/CIR/CodeGen/X86/sse-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/sse-builtins.c
@@ -8,6 +8,9 @@
 // RUN: %clang_cc1 -x c++ -flax-vector-conversions=none -ffreestanding %s -triple=x86_64-unknown-linux -target-feature +sse -fclangir -emit-llvm -o %t.ll -Wall -Werror
 // RUN: FileCheck --check-prefixes=LLVM --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/sse-builtins.c, which eventually
+// CIR shall be able to support fully.
+
 #include <immintrin.h>
 
 
@@ -18,3 +21,11 @@ void test_mm_prefetch(char const* p) {
   // CIR: cir.prefetch(%{{.*}} : !cir.ptr<!void>) locality(0) read
   // LLVM: call void @llvm.prefetch.p0(ptr {{.*}}, i32 0, i32 0, i32 1)
 }
+
+void test_mm_sfence(void) {
+  // CIR-LABEL: test_mm_sfence
+  // LLVM-LABEL: test_mm_sfence
+  _mm_sfence();
+  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse.sfence" : () -> !void
+  // LLVM: call void @llvm.x86.sse.sfence()
+}
diff --git a/clang/test/CIR/CodeGen/X86/sse2-builtins.c b/clang/test/CIR/CodeGen/X86/sse2-builtins.c
index 873d72a021f4..2524357da6a9 100644
--- a/clang/test/CIR/CodeGen/X86/sse2-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/sse2-builtins.c
@@ -8,8 +8,19 @@
 // RUN: %clang_cc1 -x c++ -flax-vector-conversions=none -ffreestanding %s -triple=x86_64-unknown-linux -target-feature +sse2 -fno-signed-char -fclangir -emit-llvm -o %t.ll -Wall -Werror
 // RUN: FileCheck --check-prefixes=LLVM-CHECK --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/sse2-builtins.c, which eventually
+// CIR shall be able to support fully.
+
 #include <immintrin.h>
 
+void test_mm_clflush(void* A) {
+  // CIR-LABEL: test_mm_clflush
+  // LLVM-LABEL: test_mm_clflush
+  _mm_clflush(A);
+  // CIR-CHECK: {{%.*}} = cir.llvm.intrinsic "x86.sse2.clflush" {{%.*}} : (!cir.ptr<!void>) -> !void
+  // LLVM-CHECK: call void @llvm.x86.sse2.clflush(ptr {{%.*}})
+}
+
 // Lowering to pextrw requires optimization.
 int test_mm_extract_epi16(__m128i A) {
     
@@ -22,3 +33,19 @@ int test_mm_extract_epi16(__m128i A) {
   // LLVM-CHECK: zext i16 %{{.*}} to i32
   return _mm_extract_epi16(A, 1);
 }
+
+void test_mm_lfence(void) {
+  // CIR-CHECK-LABEL: test_mm_lfence
+  // LLVM-CHECK-LABEL: test_mm_lfence
+  _mm_lfence();
+  // CIR-CHECK: {{%.*}} = cir.llvm.intrinsic "x86.sse2.lfence" : () -> !void
+  // LLVM-CHECK: call void @llvm.x86.sse2.lfence()
+}
+
+void test_mm_mfence(void) {
+  // CIR-CHECK-LABEL: test_mm_mfence
+  // LLVM-CHECK-LABEL: test_mm_mfence
+  _mm_mfence();
+  // CIR-CHECK: {{%.*}} = cir.llvm.intrinsic "x86.sse2.mfence" : () -> !void
+  // LLVM-CHECK: call void @llvm.x86.sse2.mfence()
+}
diff --git a/clang/test/CIR/CodeGen/X86/sse41-builtins.c b/clang/test/CIR/CodeGen/X86/sse41-builtins.c
index 59ab4b4d2bd9..814ff7bbe7eb 100644
--- a/clang/test/CIR/CodeGen/X86/sse41-builtins.c
+++ b/clang/test/CIR/CodeGen/X86/sse41-builtins.c
@@ -8,6 +8,8 @@
 // RUN: %clang_cc1 -x c -flax-vector-conversions=none -ffreestanding %s -triple=x86_64-unknown-linux -target-feature +sse4.1 -fno-signed-char -fclangir -emit-llvm -o %t.ll -Wall -Werror
 // RUN: FileCheck --check-prefix=LLVM-CHECK --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/sse41-builtins.c, which eventually
+// CIR shall be able to support fully.
 
 #include <immintrin.h>
 
diff --git a/clang/test/CIR/CodeGen/X86/x86_64-xsave.c b/clang/test/CIR/CodeGen/X86/x86_64-xsave.c
index bfa8377df521..afcd324144ee 100644
--- a/clang/test/CIR/CodeGen/X86/x86_64-xsave.c
+++ b/clang/test/CIR/CodeGen/X86/x86_64-xsave.c
@@ -43,6 +43,9 @@
 // RUN: %clang_cc1 %s -DTEST_XSAVES -O0 -triple=x86_64-unknown-linux -target-feature +xsave -target-feature +xsaves -fno-signed-char -fclangir -emit-llvm -o %t.ll -Wall -Wno-unused-but-set-variable -Werror
 // RUN: FileCheck --check-prefix=LLVM-XSAVES --input-file=%t.ll %s
 
+// This test mimics clang/test/CodeGen/X86/x86_64-xsave.c, which eventually
+// CIR shall be able to support fully.
+
 // Don't include mm_malloc.h, it's system specific.
 #define __MM_MALLOC_H
 #include <x86intrin.h>
@@ -333,4 +336,4 @@ void test(void) {
 // LLVM-XSETBV: call void @llvm.x86.xsetbv
   (void)_xsetbv(tmp_Ui, tmp_ULLi);
 #endif
-}
\ No newline at end of file
+}