diff --git a/lib/Basic/LangOptions.cpp b/lib/Basic/LangOptions.cpp
index 12b4a9b5b064e..4700781c85c95 100644
--- a/lib/Basic/LangOptions.cpp
+++ b/lib/Basic/LangOptions.cpp
@@ -246,6 +246,9 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
   case llvm::Triple::Haiku:
     addPlatformConditionValue(PlatformConditionKind::OS, "Haiku");
     break;
+  case llvm::Triple::WASI:
+    addPlatformConditionValue(PlatformConditionKind::OS, "WASI");
+    break;
   default:
     UnsupportedOS = true;
     break;
@@ -277,6 +280,12 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
   case llvm::Triple::ArchType::systemz:
     addPlatformConditionValue(PlatformConditionKind::Arch, "s390x");
     break;
+  case llvm::Triple::ArchType::wasm32:
+    addPlatformConditionValue(PlatformConditionKind::Arch, "wasm32");
+    break;
+  case llvm::Triple::ArchType::wasm64:
+    addPlatformConditionValue(PlatformConditionKind::Arch, "wasm64");
+    break;
   default:
     UnsupportedArch = true;
   }
@@ -293,6 +302,8 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
   case llvm::Triple::ArchType::ppc64le:
   case llvm::Triple::ArchType::x86:
   case llvm::Triple::ArchType::x86_64:
+  case llvm::Triple::ArchType::wasm32:
+  case llvm::Triple::ArchType::wasm64:
     addPlatformConditionValue(PlatformConditionKind::Endianness, "little");
     break;
   case llvm::Triple::ArchType::ppc64:
diff --git a/lib/Basic/Platform.cpp b/lib/Basic/Platform.cpp
index 10ebfd36c53b5..a18417073a537 100644
--- a/lib/Basic/Platform.cpp
+++ b/lib/Basic/Platform.cpp
@@ -163,8 +163,6 @@ StringRef swift::getPlatformNameForTriple(const llvm::Triple &triple) {
   case llvm::Triple::AMDPAL:
   case llvm::Triple::HermitCore:
   case llvm::Triple::Hurd:
-  case llvm::Triple::WASI:
-    return "";
   case llvm::Triple::Darwin:
   case llvm::Triple::MacOSX:
   case llvm::Triple::IOS:
@@ -191,6 +189,8 @@ StringRef swift::getPlatformNameForTriple(const llvm::Triple &triple) {
     return "ps4";
   case llvm::Triple::Haiku:
     return "haiku";
+  case llvm::Triple::WASI:
+    return "wasi";
   }
   llvm_unreachable("unsupported OS");
 }
diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index be139aa09c096..546c36f8ceb48 100644
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -265,6 +265,8 @@ Driver::buildToolChain(const llvm::opt::InputArgList &ArgList) {
     return llvm::make_unique<toolchains::Windows>(*this, target);
   case llvm::Triple::Haiku:
     return llvm::make_unique<toolchains::GenericUnix>(*this, target);
+  case llvm::Triple::WASI:
+    return llvm::make_unique<toolchains::GenericUnix>(*this, target);
   default:
     Diags.diagnose(SourceLoc(), diag::error_unknown_target,
                    ArgList.getLastArg(options::OPT_target)->getValue());
diff --git a/test/Driver/Inputs/wasm.sdk/usr/lib/swift/wasi/wasm32/Swift.swiftinterface b/test/Driver/Inputs/wasm.sdk/usr/lib/swift/wasi/wasm32/Swift.swiftinterface
new file mode 100644
index 0000000000000..ee95517943e35
--- /dev/null
+++ b/test/Driver/Inputs/wasm.sdk/usr/lib/swift/wasi/wasm32/Swift.swiftinterface
@@ -0,0 +1,3 @@
+// swift-interface-format-version: 1.0
+// swift-module-flags: -target wasm32-unknown-wasi -disable-objc-interop -swift-version 5 -O -module-name Swift -parse-stdlib
+
diff --git a/test/Driver/Inputs/wasm.sdk/usr/lib/swift/wasi/wasm64/Swift.swiftinterface b/test/Driver/Inputs/wasm.sdk/usr/lib/swift/wasi/wasm64/Swift.swiftinterface
new file mode 100644
index 0000000000000..717b6727c4148
--- /dev/null
+++ b/test/Driver/Inputs/wasm.sdk/usr/lib/swift/wasi/wasm64/Swift.swiftinterface
@@ -0,0 +1,3 @@
+// swift-interface-format-version: 1.0
+// swift-module-flags: -target wasm64-unknown-wasi -disable-objc-interop -swift-version 5 -O -module-name Swift -parse-stdlib
+
diff --git a/test/Driver/target-triple.swift b/test/Driver/target-triple.swift
new file mode 100644
index 0000000000000..99cbf7f512327
--- /dev/null
+++ b/test/Driver/target-triple.swift
@@ -0,0 +1,2 @@
+// RUN: %swiftc_driver -target wasm32-unknown-wasi -sdk %S/Inputs/wasm.sdk -typecheck %s
+// RUN: %swiftc_driver -target wasm64-unknown-wasi -sdk %S/Inputs/wasm.sdk -typecheck %s