diff --git a/stl/inc/complex b/stl/inc/complex
index 5e935cf52d0..b6b2594ac20 100644
--- a/stl/inc/complex
+++ b/stl/inc/complex
@@ -20,16 +20,16 @@
 // no intrinsics for /clr:pure
 #elif defined(__clang__)
 // TRANSITION, not using FMA intrinsics for Clang yet
-#elif defined(_M_IX86) || defined(_M_X64)
+#elif defined(_M_IX86) || (defined(_M_X64) && !defined(_M_ARM64EC))
 #define _FMP_USING_X86_X64_INTRINSICS
 #include <emmintrin.h>
 #include <isa_availability.h>
 extern "C" int __isa_available;
 extern "C" __m128d __cdecl _mm_fmsub_sd(__m128d, __m128d, __m128d);
-#elif defined(_M_ARM64)
+#elif defined(_M_ARM64) || defined(_M_ARM64EC)
 #define _FMP_USING_ARM64_INTRINSICS
 #include <arm64_neon.h>
-#endif // ^^^ defined(_M_ARM64) ^^^
+#endif // ^^^ defined(_M_ARM64) || defined(_M_ARM64EC) ^^^
 
 #pragma pack(push, _CRT_PACKING)
 #pragma warning(push, _STL_WARNING_LEVEL)
diff --git a/stl/msbuild/stl_1/msvcp_1.settings.targets b/stl/msbuild/stl_1/msvcp_1.settings.targets
index 4db7cb3f625..eb1652c4c44 100644
--- a/stl/msbuild/stl_1/msvcp_1.settings.targets
+++ b/stl/msbuild/stl_1/msvcp_1.settings.targets
@@ -33,8 +33,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <UseMsvcrt>false</UseMsvcrt>
         <GenerateImportLib>true</GenerateImportLib>
         <RCIntermediateOutputDirectory>$(IntermediateOutputDirectory)</RCIntermediateOutputDirectory>
-        <IntermediateImportLibOutput>$(CrtBuildDirNative)\msvcprt_1$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
-        <IntermediateImportLibOutputA64X>$(CrtBuildDir)\msvcprt_1$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutputA64X>
+        <IntermediateImportLibOutput>$(CrtBuildDir)\msvcprt_1$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
         <DllDefName>$(LibOutputFileName).$(MsvcpFlavor)</DllDefName>
         <DllDef>$(IntermediateOutputDirectory)\$(DllDefName).def</DllDef>
 
diff --git a/stl/msbuild/stl_2/msvcp_2.settings.targets b/stl/msbuild/stl_2/msvcp_2.settings.targets
index cfca58c4b92..79540664211 100644
--- a/stl/msbuild/stl_2/msvcp_2.settings.targets
+++ b/stl/msbuild/stl_2/msvcp_2.settings.targets
@@ -33,8 +33,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <UseMsvcrt>false</UseMsvcrt>
         <GenerateImportLib>true</GenerateImportLib>
         <RCIntermediateOutputDirectory>$(IntermediateOutputDirectory)</RCIntermediateOutputDirectory>
-        <IntermediateImportLibOutput>$(CrtBuildDirNative)\msvcprt_2$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
-        <IntermediateImportLibOutputA64X>$(CrtBuildDir)\msvcprt_2$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutputA64X>
+        <IntermediateImportLibOutput>$(CrtBuildDir)\msvcprt_2$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
         <DllDefName>$(LibOutputFileName).$(MsvcpFlavor)</DllDefName>
         <DllDef>$(IntermediateOutputDirectory)\$(DllDefName).def</DllDef>
 
diff --git a/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets b/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets
index f85149981f9..9590f000309 100644
--- a/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets
+++ b/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets
@@ -33,8 +33,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <UseMsvcrt>false</UseMsvcrt>
         <GenerateImportLib>true</GenerateImportLib>
         <RCIntermediateOutputDirectory>$(IntermediateOutputDirectory)</RCIntermediateOutputDirectory>
-        <IntermediateImportLibOutput>$(CrtBuildDirNative)\msvcprt_atomic_wait$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
-        <IntermediateImportLibOutputA64X>$(CrtBuildDir)\msvcprt_atomic_wait$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutputA64X>
+        <IntermediateImportLibOutput>$(CrtBuildDir)\msvcprt_atomic_wait$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
         <DllDefName>$(LibOutputFileName).$(MsvcpFlavor)</DllDefName>
         <DllDef>$(IntermediateOutputDirectory)\$(DllDefName).def</DllDef>
 
diff --git a/stl/msbuild/stl_base/msvcp.settings.targets b/stl/msbuild/stl_base/msvcp.settings.targets
index 3fbaa0f17ac..3dec66549c7 100644
--- a/stl/msbuild/stl_base/msvcp.settings.targets
+++ b/stl/msbuild/stl_base/msvcp.settings.targets
@@ -36,8 +36,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <UseMsvcrt>false</UseMsvcrt>
         <GenerateImportLib>true</GenerateImportLib>
         <RCIntermediateOutputDirectory>$(IntermediateOutputDirectory)</RCIntermediateOutputDirectory>
-        <IntermediateImportLibOutput>$(CrtBuildDirNative)\msvcprt_base$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
-        <IntermediateImportLibOutputA64X>$(CrtBuildDir)\msvcprt_base$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutputA64X>
+        <IntermediateImportLibOutput>$(CrtBuildDir)\msvcprt_base$(BuildSuffix).$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
         <DllDefName>$(LibOutputFileName).$(MsvcpFlavor)</DllDefName>
         <DllDef>$(IntermediateOutputDirectory)\$(DllDefName).def</DllDef>
         <ClDefines Condition="'$(DependsOnConcRT)' == 'true'">$(ClDefines);_STL_CONCRT_SUPPORT</ClDefines>
diff --git a/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets b/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets
index d913adbc158..2116ad9a688 100644
--- a/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets
+++ b/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets
@@ -33,8 +33,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <UseMsvcrt>false</UseMsvcrt>
         <GenerateImportLib>true</GenerateImportLib>
         <RCIntermediateOutputDirectory>$(IntermediateOutputDirectory)</RCIntermediateOutputDirectory>
-        <IntermediateImportLibOutput>$(CrtBuildDirNative)\msvcprt$(BuildSuffix)_codecvt_ids.$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
-        <IntermediateImportLibOutputA64X>$(CrtBuildDir)\msvcprt$(BuildSuffix)_codecvt_ids.$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutputA64X>
+        <IntermediateImportLibOutput>$(CrtBuildDir)\msvcprt$(BuildSuffix)_codecvt_ids.$(MsvcpFlavor).import_only.lib</IntermediateImportLibOutput>
         <DllDefName>$(LibOutputFileName).$(MsvcpFlavor)</DllDefName>
         <DllDef>$(IntermediateOutputDirectory)\$(DllDefName).def</DllDef>