diff --git a/clang/include/clang/Basic/Builtins.def b/clang/include/clang/Basic/Builtins.def
--- a/clang/include/clang/Basic/Builtins.def
+++ b/clang/include/clang/Basic/Builtins.def
@@ -323,6 +323,9 @@
 BUILTIN(__builtin_truncl, "LdLd", "Fnc")
 BUILTIN(__builtin_truncf16, "hh", "Fnc")
 
+// Access to floating point environment
+BUILTIN(__builtin_flt_rounds, "i", "n")
+
 // C99 complex builtins
 BUILTIN(__builtin_cabs, "dXd", "Fne")
 BUILTIN(__builtin_cabsf, "fXf", "Fne")
@@ -517,7 +520,6 @@
 BUILTIN(__builtin_extract_return_addr, "v*v*", "n")
 BUILTIN(__builtin_frame_address, "v*IUi", "n")
 BUILTIN(__builtin___clear_cache, "vc*c*", "n")
-BUILTIN(__builtin_flt_rounds, "i", "nc")
 BUILTIN(__builtin_setjmp, "iv**", "j")
 BUILTIN(__builtin_longjmp, "vv**i", "r")
 BUILTIN(__builtin_unwind_init, "v", "")
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -18270,6 +18270,46 @@
 would and handles error conditions in the same way.
 
 
+Floating Point Environment Manipulation intrinsics
+--------------------------------------------------
+
+These functions read or write floating point environment, such as rounding
+mode or state of floating point exceptions. Altering the floating point
+environment requires special care. See :ref:`Floating Point Environment <floatenv>`.
+
+'``llvm.flt.rounds``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+      declare i32 @llvm.flt.rounds()
+
+Overview:
+"""""""""
+
+The '``llvm.flt.rounds``' intrinsic reads the current rounding mode.
+
+Semantics:
+""""""""""
+
+The '``llvm.flt.rounds``' intrinsic returns the current rounding mode.
+Encoding of the returned values is same as the result of ``FLT_ROUNDS``,
+specified by C standard:
+
+::
+
+    0  - toward zero
+    1  - to nearest, ties to even
+    2  - toward positive infinity
+    3  - toward negative infinity
+    4  - to nearest, ties away from zero
+
+Other values may be used to represent additional rounding modes, supported by a
+target. These values are target-specific.
+
 General Intrinsics
 ------------------
 
diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
--- a/llvm/include/llvm/IR/Intrinsics.td
+++ b/llvm/include/llvm/IR/Intrinsics.td
@@ -612,6 +612,13 @@
                                [IntrNoMem, IntrSpeculatable, IntrWillReturn, ImmArg<1>, ImmArg<2>, ImmArg<3>]>,
                                GCCBuiltin<"__builtin_object_size">;
 
+//===--------------- Access to Floating Point Environment -----------------===//
+//
+
+let IntrProperties = [IntrInaccessibleMemOnly, IntrWillReturn] in {
+  def int_flt_rounds    : Intrinsic<[llvm_i32_ty], []>;
+}
+
 //===--------------- Constrained Floating Point Intrinsics ----------------===//
 //
 
@@ -1115,8 +1122,6 @@
 
 ///===-------------------------- Other Intrinsics --------------------------===//
 //
-def int_flt_rounds : Intrinsic<[llvm_i32_ty]>,
-                     GCCBuiltin<"__builtin_flt_rounds">;
 def int_trap : Intrinsic<[], [], [IntrNoReturn, IntrCold]>,
                GCCBuiltin<"__builtin_trap">;
 def int_debugtrap : Intrinsic<[]>,
diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.def b/llvm/include/llvm/IR/RuntimeLibcalls.def
--- a/llvm/include/llvm/IR/RuntimeLibcalls.def
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.def
@@ -548,6 +548,9 @@
 // Return address
 HANDLE_LIBCALL(RETURN_ADDRESS, nullptr)
 
+// Floating-point Environment
+HANDLE_LIBCALL(FLT_ROUNDS_, "__flt_rounds")
+
 HANDLE_LIBCALL(UNKNOWN_LIBCALL, nullptr)
 
 #undef HANDLE_LIBCALL
diff --git a/llvm/lib/CodeGen/IntrinsicLowering.cpp b/llvm/lib/CodeGen/IntrinsicLowering.cpp
--- a/llvm/lib/CodeGen/IntrinsicLowering.cpp
+++ b/llvm/lib/CodeGen/IntrinsicLowering.cpp
@@ -426,10 +426,9 @@
     break;
   }
   case Intrinsic::flt_rounds:
-     // Lower to "round to the nearest"
-     if (!CI->getType()->isVoidTy())
-       CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
-     break;
+    ReplaceCallWith("__flt_rounds", CI, CI->arg_begin(), CI->arg_end(),
+                    Type::getInt32Ty(CI->getContext()));
+    break;
   case Intrinsic::invariant_start:
   case Intrinsic::lifetime_start:
     // Discard region information.