Index: lib/Driver/ToolChains/Fuchsia.h
===================================================================
--- lib/Driver/ToolChains/Fuchsia.h
+++ lib/Driver/ToolChains/Fuchsia.h
@@ -42,6 +42,7 @@
 
   bool HasNativeLLVMSupport() const override { return true; }
   bool IsIntegratedAssemblerDefault() const override { return true; }
+  bool IsMathErrnoDefault() const override { return false; }
   RuntimeLibType GetDefaultRuntimeLibType() const override {
     return ToolChain::RLT_CompilerRT;
   }
Index: test/Driver/fast-math.c
===================================================================
--- test/Driver/fast-math.c
+++ test/Driver/fast-math.c
@@ -93,6 +93,8 @@
 // RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
 // RUN: %clang -### -target x86_64-unknown-dragonfly -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
+// RUN: %clang -### -target x86_64-fuchsia -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
 //
 // Check that -ffast-math disables -fmath-errno, and -fno-fast-math merely
 // preserves the target default. Also check various flag set operations between