diff --git a/build-icu.ps1 b/build-icu.ps1
index 2ceca7608c55..338b3d368a96 100644
--- a/build-icu.ps1
+++ b/build-icu.ps1
@@ -76,11 +76,14 @@ if (-not (Test-Path $ICU_SOURCE_DIR)) {
 }
 
 if ($Platform -eq "x64") {
-    $ArchFlag = if ($Baseline) { "/arch:SSE2" } else { "/arch:AVX2" }
+    $ArchFlag = if ($Baseline) { "/clang:-march=nehalem" } else { "/clang:-march=haswell" }
 } else {
     $ArchFlag = ""
 }
 
+# ClangCL for stage 2 so -march= limits codegen (MSVC /arch:SSE2 is a no-op on x64).
+$ToolsetArg = if ($Platform -eq "x64") { @("/p:PlatformToolset=ClangCL") } else { @() }
+
 # --- Function to patch vcxproj files for static library build with /MT ---
 function Patch-IcuVcxProj {
     param(
@@ -125,6 +128,10 @@ function Patch-IcuVcxProj {
     $content = $content -replace '<OutputFile>[^<]*\.(dll|DLL)</OutputFile>', ''
     $content = $content -replace '<ImportLibrary>[^<]*</ImportLibrary>', ''
 
+    # Strip .rc — rc.exe cannot parse clang stddef.h and static libs do not need version resources.
+    $content = $content -replace "(?s)<ResourceCompile[^>]*>.*?</ResourceCompile>", ""
+    $content = $content -replace "<ResourceCompile[^>]*/>", ""
+
     # For stubdata - remove resource-only DLL settings
     if ($FilePath -match "stubdata") {
         $content = $content -replace '<NoEntryPoint>true</NoEntryPoint>', ''
@@ -235,6 +242,7 @@ foreach ($target in @("common", "i18n")) {
         "/v:minimal"
     )
 
+    $buildArgs += $ToolsetArg
     & $msbuildPath $buildArgs
 
     if ($LASTEXITCODE -ne 0) {