Index: lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -997,6 +997,22 @@
       return EraseInstFromFunction(CI);
     break;
   }
+  case Intrinsic::assume: {
+    // Canonicalize assume(a && b) -> assume(a); assume(b);
+    Value *IIOperand = II->getArgOperand(0), *A, *B;
+    if (match(IIOperand, m_And(m_Value(A), m_Value(B)))) {
+      Builder->CreateCall(II->getCalledValue(), A, II->getName());
+      Builder->CreateCall(II->getCalledValue(), B, II->getName());
+      return EraseInstFromFunction(*II);
+    }
+    // assume(!(a || b)) -> assume(!a); assume(!b);
+    if (match(IIOperand, m_Not(m_Or(m_Value(A), m_Value(B))))) {
+      Builder->CreateCall(II->getCalledValue(), Builder->CreateNot(A), II->getName());
+      Builder->CreateCall(II->getCalledValue(), Builder->CreateNot(B), II->getName());
+      return EraseInstFromFunction(*II);
+    }
+    break;
+  }
   }
 
   return visitCallSite(II);
Index: test/Transforms/InstCombine/assume.ll
===================================================================
--- test/Transforms/InstCombine/assume.ll
+++ test/Transforms/InstCombine/assume.ll
@@ -140,7 +140,39 @@
 ; CHECK-LABEL: @icmp2
 ; CHECK: call void @llvm.assume
 ; CHECK: ret i32 0
+}
+
+; Function Attrs: nounwind uwtable
+define i32 @can1(i1 %a, i1 %b, i1 %c) {
+entry:
+  %and1 = and i1 %a, %b
+  %and  = and i1 %and1, %c
+  tail call void @llvm.assume(i1 %and)
+
+; CHECK-LABEL: @can1
+; CHECK: call void @llvm.assume(i1 %a)
+; CHECK: call void @llvm.assume(i1 %b)
+; CHECK: call void @llvm.assume(i1 %c)
+; CHECK: ret i32
+
+  ret i32 5
+}
+
+; Function Attrs: nounwind uwtable
+define i32 @can2(i1 %a, i1 %b, i1 %c) {
+entry:
+  %v = or i1 %a, %b
+  %w = xor i1 %v, 1
+  tail call void @llvm.assume(i1 %w)
+
+; CHECK-LABEL: @can2
+; CHECK: %[[V1:[^ ]+]] = xor i1 %a, true
+; CHECK: call void @llvm.assume(i1 %[[V1]])
+; CHECK: %[[V2:[^ ]+]] = xor i1 %b, true
+; CHECK: call void @llvm.assume(i1 %[[V2]])
+; CHECK: ret i32
 
+  ret i32 5
 }
 
 attributes #0 = { nounwind uwtable }