diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index d76cad2..3ec4040 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -2407,13 +2407,17 @@
   if (CGF.SanOpts->Shift && !CGF.getLangOpts().OpenCL &&
       isa<llvm::IntegerType>(Ops.LHS->getType())) {
     llvm::Value *WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
-    // FIXME: Emit the branching explicitly rather than emitting the check
-    // twice.
-    EmitBinOpCheck(Builder.CreateICmpULE(RHS, WidthMinusOne), Ops);
+    llvm::Value *Valid = Builder.CreateICmpULE(RHS, WidthMinusOne);
 
     if (Ops.Ty->hasSignedIntegerRepresentation()) {
+      llvm::BasicBlock *Orig = Builder.GetInsertBlock();
+      llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
+      llvm::BasicBlock *CheckBitsShifted = CGF.createBasicBlock("check");
+      Builder.CreateCondBr(Valid, CheckBitsShifted, Cont);
+
       // Check whether we are shifting any non-zero bits off the top of the
       // integer.
+      CGF.EmitBlock(CheckBitsShifted);
       llvm::Value *BitsShiftedOff =
         Builder.CreateLShr(Ops.LHS,
                            Builder.CreateSub(WidthMinusOne, RHS, "shl.zeros",
@@ -2428,8 +2432,15 @@
         BitsShiftedOff = Builder.CreateLShr(BitsShiftedOff, One);
       }
       llvm::Value *Zero = llvm::ConstantInt::get(BitsShiftedOff->getType(), 0);
-      EmitBinOpCheck(Builder.CreateICmpEQ(BitsShiftedOff, Zero), Ops);
+      llvm::Value *SecondCheck = Builder.CreateICmpEQ(BitsShiftedOff, Zero);
+      CGF.EmitBlock(Cont);
+      llvm::PHINode *P = Builder.CreatePHI(Valid->getType(), 2);
+      P->addIncoming(Valid, Orig);
+      P->addIncoming(SecondCheck, CheckBitsShifted);
+      Valid = P;
     }
+
+    EmitBinOpCheck(Valid, Ops);
   }
   // OpenCL 6.3j: shift values are effectively % word size of LHS.
   if (CGF.getLangOpts().OpenCL)
diff --git a/test/CodeGen/catch-undef-behavior.c b/test/CodeGen/catch-undef-behavior.c
index cd86dd5..3e180a4 100644
--- a/test/CodeGen/catch-undef-behavior.c
+++ b/test/CodeGen/catch-undef-behavior.c
@@ -8,8 +8,7 @@
 // FIXME: When we only emit each type once, use [[INT]] more below.
 // CHECK: @[[LINE_100:.*]] = private unnamed_addr global {{.*}}, i32 100, i32 5 {{.*}} @[[INT]], i64 4, i8 1
 // CHECK: @[[LINE_200:.*]] = {{.*}}, i32 200, i32 10 {{.*}}, i64 4, i8 0
-// CHECK: @[[LINE_300_A:.*]] = {{.*}}, i32 300, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
-// CHECK: @[[LINE_300_B:.*]] = {{.*}}, i32 300, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
+// CHECK: @[[LINE_300:.*]] = {{.*}}, i32 300, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
 // CHECK: @[[LINE_400:.*]] = {{.*}}, i32 400, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
 // CHECK: @[[LINE_500:.*]] = {{.*}}, i32 500, i32 10 {{.*}} @{{.*}}, i64 4, i8 0 }
 // CHECK: @[[LINE_600:.*]] = {{.*}}, i32 600, i32 3 {{.*}} @{{.*}}, i64 4, i8 1 }
@@ -106,35 +105,36 @@
 // CHECK-TRAP: @lsh_overflow
 int lsh_overflow(int a, int b) {
   // CHECK:      %[[INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
-  // CHECK-NEXT: br i1 %[[INBOUNDS]]
+  // CHECK-NEXT: br i1 %[[INBOUNDS]], label %[[CHECKBB:.*]], label %[[CONTBB:.*]]
 
   // CHECK-TRAP:      %[[INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
-  // CHECK-TRAP-NEXT: br i1 %[[INBOUNDS]]
-
-  // FIXME: Only emit one trap block here.
-  // CHECK:      %[[ARG1:.*]] = zext
-  // CHECK-NEXT: %[[ARG2:.*]] = zext
-  // CHECK-NEXT: call void @__ubsan_handle_shift_out_of_bounds(i8* bitcast ({{.*}} @[[LINE_300_A]] to i8*), i64 %[[ARG1]], i64 %[[ARG2]])
-
-  // CHECK-TRAP:      call void @llvm.trap() [[NR_NUW]]
-  // CHECK-TRAP-NEXT: unreachable
+  // CHECK-TRAP-NEXT: br i1 %[[INBOUNDS]], label %[[CHECKBB:.*]], label %[[CONTBB:.*]]
 
   // CHECK:      %[[SHIFTED_OUT_WIDTH:.*]] = sub nuw nsw i32 31, %[[RHS]]
   // CHECK-NEXT: %[[SHIFTED_OUT:.*]] = lshr i32 %[[LHS:.*]], %[[SHIFTED_OUT_WIDTH]]
   // CHECK-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT]], 0
-  // CHECK-NEXT: br i1 %[[NO_OVERFLOW]], {{.*}} !prof ![[WEIGHT_MD]]
+  // CHECK-NEXT: br label %[[CONTBB]]
 
   // CHECK-TRAP:      %[[SHIFTED_OUT_WIDTH:.*]] = sub nuw nsw i32 31, %[[RHS]]
   // CHECK-TRAP-NEXT: %[[SHIFTED_OUT:.*]] = lshr i32 %[[LHS:.*]], %[[SHIFTED_OUT_WIDTH]]
   // CHECK-TRAP-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT]], 0
-  // CHECK-TRAP-NEXT: br i1 %[[NO_OVERFLOW]]
+  // CHECK-TRAP-NEXT: br label %[[CONTBB]]
+
+  // CHECK:      %[[VALID:.*]] = phi i1 [ %[[INBOUNDS]], {{.*}} ], [ %[[NO_OVERFLOW]], %[[CHECKBB]] ]
+  // CHECK-NEXT: br i1 %[[VALID]], {{.*}} !prof ![[WEIGHT_MD]]
+
+  // CHECK-TRAP:      %[[VALID:.*]] = phi i1 [ %[[INBOUNDS]], {{.*}} ], [ %[[NO_OVERFLOW]], %[[CHECKBB]] ]
+  // CHECK-TRAP-NEXT: br i1 %[[VALID]]
+
 
   // CHECK:      %[[ARG1:.*]] = zext
   // CHECK-NEXT: %[[ARG2:.*]] = zext
-  // CHECK-NEXT: call void @__ubsan_handle_shift_out_of_bounds(i8* bitcast ({{.*}} @[[LINE_300_B]] to i8*), i64 %[[ARG1]], i64 %[[ARG2]])
+  // CHECK-NEXT: call void @__ubsan_handle_shift_out_of_bounds(i8* bitcast ({{.*}} @[[LINE_300]] to i8*), i64 %[[ARG1]], i64 %[[ARG2]])
+  // CHECK-NOT:  call void @__ubsan_handle_shift_out_of_bounds
 
   // CHECK-TRAP:      call void @llvm.trap() [[NR_NUW]]
-  // CHECK-TRAP-NEXT: unreachable
+  // CHECK-TRAP:      unreachable
+  // CHECK-TRAP-NOT:  call void @llvm.trap()
 
   // CHECK:      %[[RET:.*]] = shl i32 %[[LHS]], %[[RHS]]
   // CHECK-NEXT: ret i32 %[[RET]]
diff --git a/test/CodeGenCXX/catch-undef-behavior.cpp b/test/CodeGenCXX/catch-undef-behavior.cpp
index 31958a6..d6d0edf 100644
--- a/test/CodeGenCXX/catch-undef-behavior.cpp
+++ b/test/CodeGenCXX/catch-undef-behavior.cpp
@@ -130,7 +130,12 @@
   // CHECK-NEXT: %[[SHIFTED_OUT_NOT_SIGN:.*]] = lshr i32 %[[SHIFTED_OUT]], 1
 
   // CHECK-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT_NOT_SIGN]], 0
-  // CHECK-NEXT: br i1 %[[NO_OVERFLOW]]
+
+  // CHECK: %[[VALID:.*]] = phi i1 [ %[[INBOUNDS]], {{.*}} ], [ %[[NO_OVERFLOW]], {{.*}} ]
+  // CHECK-NEXT: br i1 %[[VALID]]
+
+  // CHECK: call void @__ubsan_handle_shift_out_of_bounds
+  // CHECK-NOT: call void @__ubsan_handle_shift_out_of_bounds
 
   // CHECK: %[[RET:.*]] = shl i32 %[[LHS]], %[[RHS]]
   // CHECK-NEXT: ret i32 %[[RET]]