Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -79,6 +79,13 @@
     cl::desc("Maximum number of elements in atomic memcpy the optimizer is "
              "allowed to unfold"));
 
+static cl::opt<unsigned> GuardWideningWindow(
+    "instcombine-guard-widening-window",
+    cl::init(3),
+    cl::desc("How wide an instruction window to bypass looking for "
+             "another guard"));
+
+
 /// Return the specified type promoted as it would be to pass though a va_arg
 /// area.
 static Type *getPromotedType(Type *Ty) {
@@ -3624,8 +3631,16 @@
   }
 
   case Intrinsic::experimental_guard: {
-    // Is this guard followed by another guard?
+    // Is this guard followed by another guard?  We scan forward over a small
+    // fixed window of instructions to handle common cases with conditions
+    // computed between guards.
     Instruction *NextInst = II->getNextNode();
+    for (int i = 0; i < GuardWideningWindow; i++) {
+      // Note: Using context-free form to avoid compile time blow up
+      if (!isSafeToSpeculativelyExecute(NextInst))
+        break;
+      NextInst = NextInst->getNextNode();
+    }
     Value *NextCond = nullptr;
     if (match(NextInst,
               m_Intrinsic<Intrinsic::experimental_guard>(m_Value(NextCond)))) {
@@ -3636,6 +3651,12 @@
         return eraseInstFromFunction(*NextInst);
 
       // Otherwise canonicalize guard(a); guard(b) -> guard(a & b).
+      Instruction* MoveI = II->getNextNode();
+      while (MoveI != NextInst) {
+        auto *Temp = MoveI;
+        MoveI = MoveI->getNextNode();
+        Temp->moveBefore(II);
+      }
       II->setArgOperand(0, Builder.CreateAnd(CurrCond, NextCond));
       return eraseInstFromFunction(*NextInst);
     }
Index: llvm/trunk/test/Transforms/InstCombine/call-guard.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/call-guard.ll
+++ llvm/trunk/test/Transforms/InstCombine/call-guard.ll
@@ -30,3 +30,81 @@
   call void(i1, ...) @llvm.experimental.guard( i1 %C, i32 789 )[ "deopt"() ]
   ret void
 }
+
+; This version tests for the common form where the conditions are
+; between the guards
+define void @test_guard_adjacent_diff_cond2(i32 %V1, i32 %V2) {
+; CHECK-LABEL: @test_guard_adjacent_diff_cond2(
+; CHECK-NEXT:    %1 = and i32 %V1, %V2
+; CHECK-NEXT:    %2 = icmp slt i32 %1, 0
+; CHECK-NEXT:    %and = and i32 %V1, 255
+; CHECK-NEXT:    %C = icmp ult i32 %and, 129
+; CHECK-NEXT:    %3 = and i1 %2, %C
+; CHECK-NEXT:    call void (i1, ...) @llvm.experimental.guard(i1 %3, i32 123) [ "deopt"() ]
+; CHECK-NEXT:    ret void
+  %A = icmp slt i32 %V1, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %A, i32 123 )[ "deopt"() ]
+  %B = icmp slt i32 %V2, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %B, i32 456 )[ "deopt"() ]
+  %and = and i32 %V1, 255
+  %C = icmp sle i32 %and, 128
+  call void(i1, ...) @llvm.experimental.guard( i1 %C, i32 789 )[ "deopt"() ]
+  ret void
+}
+
+; Might not be legal to hoist the load above the first guard since the
+; guard might control dereferenceability
+define void @negative_load(i32 %V1, i32* %P) {
+; CHECK-LABEL: @negative_load
+; CHECK:    @llvm.experimental.guard
+; CHECK:    @llvm.experimental.guard
+  %A = icmp slt i32 %V1, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %A, i32 123 )[ "deopt"() ]
+  %V2 = load i32, i32* %P
+  %B = icmp slt i32 %V2, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %B, i32 456 )[ "deopt"() ]
+  ret void
+}
+
+define void @deref_load(i32 %V1, i32* dereferenceable(4) %P) {
+; CHECK-LABEL: @deref_load
+; CHECK-NEXT:  %V2 = load i32, i32* %P, align 4
+; CHECK-NEXT:  %1 = and i32 %V2, %V1
+; CHECK-NEXT:  %2 = icmp slt i32 %1, 0
+; CHECK-NEXT:  call void (i1, ...) @llvm.experimental.guard(i1 %2, i32 123) [ "deopt"() ]
+  %A = icmp slt i32 %V1, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %A, i32 123 )[ "deopt"() ]
+  %V2 = load i32, i32* %P
+  %B = icmp slt i32 %V2, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %B, i32 456 )[ "deopt"() ]
+  ret void
+}
+
+; The divide might fault above the guard
+define void @negative_div(i32 %V1, i32 %D) {
+; CHECK-LABEL: @negative_div
+; CHECK:    @llvm.experimental.guard
+; CHECK:    @llvm.experimental.guard
+  %A = icmp slt i32 %V1, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %A, i32 123 )[ "deopt"() ]
+  %V2 = udiv i32 %V1, %D 
+  %B = icmp slt i32 %V2, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %B, i32 456 )[ "deopt"() ]
+  ret void
+}
+
+; Highlight the limit of the window in a case which would otherwise be mergable
+define void @negative_window(i32 %V1, i32 %a, i32 %b, i32 %c, i32 %d) {
+; CHECK-LABEL: @negative_window
+; CHECK:    @llvm.experimental.guard
+; CHECK:    @llvm.experimental.guard
+  %A = icmp slt i32 %V1, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %A, i32 123 )[ "deopt"() ]
+  %V2 = add i32 %a, %b
+  %V3 = add i32 %V2, %c
+  %V4 = add i32 %V3, %d
+  %B = icmp slt i32 %V4, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %B, i32 456 )[ "deopt"() ]
+  ret void
+}
+