diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -288,6 +288,13 @@
     Wasm,
     XCOFF,
   };
+  enum RTLibType {
+    UnknownRTLib,
+
+    COMPILER_RT,
+    LIB_GCC,
+    WINDOWS_RT,
+  };
 
 private:
   std::string Data;
@@ -363,6 +370,9 @@
   /// Get the parsed operating system type of this triple.
   OSType getOS() const { return OS; }
 
+  /// Get the rtlib implied by this triple.
+  RTLibType getRTLib() const;
+
   /// Does this triple have the optional environment (fourth) component?
   bool hasEnvironment() const {
     return getEnvironmentName() != "";
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2307,10 +2307,12 @@
     setLibcallName(RTLIB::SRA_I128, nullptr);
     setLibcallName(RTLIB::MUL_I128, nullptr);
     // The MULO libcall is not part of libgcc, only compiler-rt.
-    setLibcallName(RTLIB::MULO_I64, nullptr);
+    if (Subtarget.getTargetTriple().getRTLib() != Triple::COMPILER_RT)
+      setLibcallName(RTLIB::MULO_I64, nullptr);
   }
   // The MULO libcall is not part of libgcc, only compiler-rt.
-  setLibcallName(RTLIB::MULO_I128, nullptr);
+  if (Subtarget.getTargetTriple().getRTLib() != Triple::COMPILER_RT)
+    setLibcallName(RTLIB::MULO_I128, nullptr);
 
   // Combine sin / cos into _sincos_stret if it is available.
   if (getLibcallName(RTLIB::SINCOS_STRET_F32) != nullptr &&
diff --git a/llvm/lib/TargetParser/Triple.cpp b/llvm/lib/TargetParser/Triple.cpp
--- a/llvm/lib/TargetParser/Triple.cpp
+++ b/llvm/lib/TargetParser/Triple.cpp
@@ -1225,6 +1225,29 @@
   return parseVersionFromName(OSName);
 }
 
+Triple::RTLibType Triple::getRTLib() const {
+  if (isAndroid() || isOSDarwin() || isOSFuchsia())
+    return COMPILER_RT;
+
+  if (isGNUEnvironment()) {
+    if (isOSWindows())
+      return UnknownRTLib;
+    return LIB_GCC;
+  }
+
+  if (isOSWindows())
+    return WINDOWS_RT;
+
+  // TODO: more conditions, look at GetDefaultRuntimeLibType in clang for
+  // inspiration.
+  // Looks like AIX uses compiler-rt.
+  // "bare metal" uses compiler-rt.
+  // Fuchsia uses compiler-rt.
+  // openbsd uses compiler-rt.
+  // wasm uses compiler-rt.
+  return UnknownRTLib;
+}
+
 bool Triple::getMacOSXVersion(VersionTuple &Version) const {
   Version = getOSVersion();
 
diff --git a/llvm/test/CodeGen/X86/overflow-intrinsic-optimizations.ll b/llvm/test/CodeGen/X86/overflow-intrinsic-optimizations.ll
--- a/llvm/test/CodeGen/X86/overflow-intrinsic-optimizations.ll
+++ b/llvm/test/CodeGen/X86/overflow-intrinsic-optimizations.ll
@@ -1,8 +1,10 @@
-; RUN: llc %s -mtriple=i386 -o - | FileCheck %s
+; RUN: llc %s -mtriple=i386-linux-gnu -o - | FileCheck %s --check-prefix=CHECK-LIBGCC
+; RUN: llc %s -mtriple=i386 -o - | FileCheck %s --check-prefix=CHECK-COMPILERRT
 
 define i1 @no__mulodi4(i32 %a, i64 %b, ptr %c) {
 ; CHECK-LABEL: no__mulodi4:
-; CHECK-NOT: calll __mulodi4
+; CHECK-LIBGCC-NOT: calll __mulodi4
+; CHECK-COMPILERRT: calll __mulodi4
 entry:
   %0 = sext i32 %a to i64
   %1 = call { i64, i1 } @llvm.smul.with.overflow.i64(i64 %0, i64 %b)
diff --git a/llvm/unittests/TargetParser/TargetParserTest.cpp b/llvm/unittests/TargetParser/TargetParserTest.cpp
--- a/llvm/unittests/TargetParser/TargetParserTest.cpp
+++ b/llvm/unittests/TargetParser/TargetParserTest.cpp
@@ -1803,4 +1803,33 @@
   }
 }
 
+static Triple::RTLibType RT(const char* triple) {
+  llvm::Triple Triple(llvm::Triple::normalize(triple));
+  return Triple.getRTLib();
+}
+
+TEST(TargetParserTest, getRTLib) {
+  const char* compiler_rt_triples [] = {
+    "aarch64-linux-android", "aarch64-apple-ios", "x86_64-fuchsia",
+  };
+  const char* lib_gcc_triples [] = {
+    "x86_64-linux-gnu",
+  };
+  const char* windows_rt_triples [] = {
+    "x86_64-pc-windows-msvc"
+  };
+  const char* unknown_rt_triples [] = {
+    "x86_64-w64-mingw32", "x86_64-pc-mingw32", "i386-pc-mingw32",
+    "i686-pc-mingw32", "x86_64-w64-windows-gnu", "i686-w64-windows-gnu"
+  };
+  for (const char* T : compiler_rt_triples)
+    EXPECT_EQ(RT(T), Triple::COMPILER_RT);
+  for (const char* T : lib_gcc_triples)
+    EXPECT_EQ(RT(T), Triple::LIB_GCC);
+  for (const char* T : windows_rt_triples)
+    EXPECT_EQ(RT(T), Triple::WINDOWS_RT);
+  for (const char* T : unknown_rt_triples)
+    EXPECT_EQ(RT(T), Triple::UnknownRTLib);
+}
+
 } // namespace