diff --git a/deps/flexdis86 b/deps/flexdis86
index 1d88cb56f6..e8b6c38a65 160000
--- a/deps/flexdis86
+++ b/deps/flexdis86
@@ -1 +1 @@
-Subproject commit 1d88cb56f611713605f4c236beaebbcd80a3efa0
+Subproject commit e8b6c38a6590e65efa0255124993a61f9f68c3ec
diff --git a/deps/macaw b/deps/macaw
index 6a83d23989..3a071e317b 160000
--- a/deps/macaw
+++ b/deps/macaw
@@ -1 +1 @@
-Subproject commit 6a83d23989a44eb7b57b411e7fb2c425d2d95565
+Subproject commit 3a071e317b456515a1d193bd5180a9127700c408
diff --git a/intTests/test_llvm_x86_06/test.S b/intTests/test_llvm_x86_06/test.S
new file mode 100644
index 0000000000..b84a3ffeef
--- /dev/null
+++ b/intTests/test_llvm_x86_06/test.S
@@ -0,0 +1,14 @@
+section .bss
+section .text
+foo:
+	ret
+global discoverytest
+discoverytest:
+        lea rax, [rsp]
+	call foo
+        lea rsp, [rax]
+        ret
+global _start
+_start:
+        mov rax, 60
+        syscall
diff --git a/intTests/test_llvm_x86_06/test.c b/intTests/test_llvm_x86_06/test.c
new file mode 100644
index 0000000000..c53d0d4e9c
--- /dev/null
+++ b/intTests/test_llvm_x86_06/test.c
@@ -0,0 +1,8 @@
+#include <stdint.h>
+#include <stdio.h>
+
+extern void discoverytest();
+
+void test() {
+	discoverytest();
+};
diff --git a/intTests/test_llvm_x86_06/test.saw b/intTests/test_llvm_x86_06/test.saw
new file mode 100644
index 0000000000..e3c64e334d
--- /dev/null
+++ b/intTests/test_llvm_x86_06/test.saw
@@ -0,0 +1,13 @@
+enable_experimental;
+
+m <- llvm_load_module "test.bc";
+
+let discoverytest_setup = do {
+  crucible_execute_func [];
+};
+
+fails (crucible_llvm_verify_x86 m "./test" "discoverytest" [] false discoverytest_setup w4);
+
+add_x86_preserved_reg "rax";
+crucible_llvm_verify_x86 m "./test" "discoverytest" [] false discoverytest_setup w4;
+default_x86_preserved_reg;
\ No newline at end of file
diff --git a/intTests/test_llvm_x86_06/test.sh b/intTests/test_llvm_x86_06/test.sh
new file mode 100755
index 0000000000..79a0867031
--- /dev/null
+++ b/intTests/test_llvm_x86_06/test.sh
@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+
+yasm -felf64 test.S
+ld test.o -o test
+clang -c -emit-llvm test.c
+$SAW test.saw
diff --git a/src/SAWScript/Crucible/LLVM/X86.hs b/src/SAWScript/Crucible/LLVM/X86.hs
index 66bcdb10c9..7b5389a9b8 100644
--- a/src/SAWScript/Crucible/LLVM/X86.hs
+++ b/src/SAWScript/Crucible/LLVM/X86.hs
@@ -39,8 +39,10 @@ import Data.Foldable (foldlM)
 import qualified Data.List.NonEmpty as NE
 import qualified Data.Vector as Vector
 import qualified Data.Text as Text
+import Data.Text (Text)
 import Data.Text.Encoding (decodeUtf8, encodeUtf8)
 import qualified Data.Set as Set
+import Data.Set (Set)
 import qualified Data.Map as Map
 import Data.Map (Map)
 import Data.Maybe
@@ -170,6 +172,27 @@ getReg reg regs = case Macaw.lookupX86Reg reg regs of
   Just (C.RV val) -> pure val
   Nothing -> throwX86 $ mconcat ["Invalid register: ", show reg]
 
+-- TODO: extend to more than general purpose registers
+stringToReg :: Text -> Maybe (Some Macaw.X86Reg)
+stringToReg s = case s of
+  "rax" -> Just $ Some Macaw.RAX
+  "rbx" -> Just $ Some Macaw.RBX
+  "rcx" -> Just $ Some Macaw.RCX
+  "rdx" -> Just $ Some Macaw.RDX
+  "rsp" -> Just $ Some Macaw.RSP
+  "rbp" -> Just $ Some Macaw.RBP
+  "rsi" -> Just $ Some Macaw.RSI
+  "rdi" -> Just $ Some Macaw.RDI
+  "r8" -> Just $ Some Macaw.R8
+  "r9" -> Just $ Some Macaw.R9
+  "r10" -> Just $ Some Macaw.R10
+  "r11" -> Just $ Some Macaw.R11
+  "r12" -> Just $ Some Macaw.R12
+  "r13" -> Just $ Some Macaw.R13
+  "r14" -> Just $ Some Macaw.R14
+  "r15" -> Just $ Some Macaw.R15
+  _ -> Nothing
+
 cryptolUninterpreted ::
   (MonadIO m, MonadThrow m) =>
   CryptolEnv ->
@@ -217,11 +240,17 @@ crucible_llvm_verify_x86 bic opts (Some (llvmModule :: LLVMModule x)) path nm gl
       halloc <- getHandleAlloc
       let mvar = C.LLVM.llvmMemVar . view C.LLVM.transContext $ modTrans llvmModule
       sfs <- liftIO $ Macaw.newSymFuns sym
-      cenv <- rwCryptol <$> getTopLevelRW
+      rw <- getTopLevelRW
+      let cenv = rwCryptol rw
       liftIO $ C.sawRegisterSymFunInterp sym (Macaw.fnAesEnc sfs) $ cryptolUninterpreted cenv "aesenc"
       liftIO $ C.sawRegisterSymFunInterp sym (Macaw.fnAesEncLast sfs) $ cryptolUninterpreted cenv "aesenclast"
+      liftIO $ C.sawRegisterSymFunInterp sym (Macaw.fnAesDec sfs) $ cryptolUninterpreted cenv "aesdec"
+      liftIO $ C.sawRegisterSymFunInterp sym (Macaw.fnAesDecLast sfs) $ cryptolUninterpreted cenv "aesdeclast"
+      liftIO $ C.sawRegisterSymFunInterp sym (Macaw.fnAesKeyGenAssist sfs) $ cryptolUninterpreted cenv "aeskeygenassist"
+      liftIO $ C.sawRegisterSymFunInterp sym (Macaw.fnClMul sfs) $ cryptolUninterpreted cenv "clmul"
 
-      (C.SomeCFG cfg, elf, relf, addr, cfgs) <- liftIO $ buildCFG opts halloc path nm
+      let preserved = Set.fromList . catMaybes $ stringToReg . Text.toLower . Text.pack <$> rwPreservedRegs rw
+      (C.SomeCFG cfg, elf, relf, addr, cfgs) <- liftIO $ buildCFG opts halloc preserved path nm
       addrInt <- if Macaw.segmentBase (Macaw.segoffSegment addr) == 0
         then pure . toInteger $ Macaw.segmentOffset (Macaw.segoffSegment addr) + Macaw.segoffOffset addr
         else fail $ mconcat ["Address of \"", nm, "\" is not an absolute address"]
@@ -334,6 +363,7 @@ crucible_llvm_verify_x86 bic opts (Some (llvmModule :: LLVMModule x)) path nm gl
 buildCFG ::
   Options ->
   C.HandleAllocator ->
+  Set (Some Macaw.X86Reg) {- ^ Registers to treat as callee-saved -} ->
   String {- ^ Path to ELF file -} ->
   String {- ^ Function's symbol in ELF file -} ->
   IO ( C.SomeCFG
@@ -350,7 +380,7 @@ buildCFG ::
          (EmptyCtx ::> Macaw.ArchRegStruct Macaw.X86_64)
          (Macaw.ArchRegStruct Macaw.X86_64))
      )
-buildCFG opts halloc path nm = do
+buildCFG opts halloc preserved path nm = do
   printOutLn opts Info $ mconcat ["Finding symbol for \"", nm, "\""]
   elf <- getElf path
   relf <- getRelevant elf
@@ -360,10 +390,17 @@ buildCFG opts halloc path nm = do
       _ -> fail $ mconcat ["Could not find symbol \"", nm, "\""]
   printOutLn opts Info $ mconcat ["Found symbol at address ", show addr, ", building CFG"]
   let
+    preservedRegs = Set.union preserved Macaw.x86CalleeSavedRegs
+    preserveFn :: forall t. Macaw.X86Reg t -> Bool
+    preserveFn r = Set.member (Some r) preservedRegs
+    macawCallParams = Macaw.x86_64CallParams { Macaw.preserveReg = preserveFn }
+    macawArchInfo = (Macaw.x86_64_info preserveFn)
+      { Macaw.archCallParams = macawCallParams
+      }
     initialDiscoveryState =
-      Macaw.emptyDiscoveryState (memory relf) (funSymMap relf) Macaw.x86_64_linux_info
+      Macaw.emptyDiscoveryState (memory relf) (funSymMap relf) macawArchInfo
+      -- "inline" any function addresses that we happen to jump to
       & Macaw.trustedFunctionEntryPoints .~ Set.empty
-  let
     finalState = Macaw.cfgFromAddrsAndState initialDiscoveryState [addr] []
     finfos = finalState ^. Macaw.funInfo
   cfgs <- forM finfos $ \(Some finfo) ->
@@ -790,6 +827,7 @@ assertPointsTo env tyenv nameEnv (LLVMPointsTo _ cond tptr tptexpected) = do
   ptr <- resolvePtrSetupValue env tyenv tptr
   memTy <- liftIO $ typeOfSetupValue cc tyenv nameEnv texpected
   storTy <- liftIO $ C.LLVM.toStorableType memTy
+
   actual <- liftIO $ C.LLVM.assertSafe sym =<< C.LLVM.loadRaw sym mem ptr storTy C.LLVM.noAlignment
   pure $ LO.matchArg opts sc cc ms MS.PostState actual memTy texpected
 
diff --git a/src/SAWScript/Interpreter.hs b/src/SAWScript/Interpreter.hs
index ddd7f9d671..0db2d1e145 100644
--- a/src/SAWScript/Interpreter.hs
+++ b/src/SAWScript/Interpreter.hs
@@ -434,6 +434,7 @@ buildTopLevelEnv proxy opts =
                    , rwProfilingFile = Nothing
                    , rwLaxArith = False
                    , rwWhat4HashConsing = False
+                   , rwPreservedRegs = []
                    }
        return (bic, ro0, rw0)
 
@@ -508,6 +509,16 @@ disable_what4_hash_consing = do
   rw <- getTopLevelRW
   putTopLevelRW rw { rwWhat4HashConsing = False }
 
+add_x86_preserved_reg :: String -> TopLevel ()
+add_x86_preserved_reg r = do
+  rw <- getTopLevelRW
+  putTopLevelRW rw { rwPreservedRegs = r:rwPreservedRegs rw }
+
+default_x86_preserved_reg :: TopLevel ()
+default_x86_preserved_reg = do
+  rw <- getTopLevelRW
+  putTopLevelRW rw { rwPreservedRegs = [] }
+
 include_value :: FilePath -> TopLevel ()
 include_value file = do
   oldpath <- io $ getCurrentDirectory
@@ -2203,6 +2214,16 @@ primitives = Map.fromList
     , "that can be used as an override when verifying other LLVM functions."
     ]
 
+  , prim "add_x86_preserved_reg" "String -> TopLevel ()"
+    (pureVal add_x86_preserved_reg)
+    Current
+    [ "Treat the given register as callee-saved during x86 verification." ]
+
+  , prim "default_x86_preserved_reg" "TopLevel ()"
+    (pureVal default_x86_preserved_reg)
+    Current
+    [ "Use the default set of callee-saved registers during x86 verification.." ]
+
   , prim "crucible_array"
     "[SetupValue] -> SetupValue"
     (pureVal CIR.anySetupArray)
diff --git a/src/SAWScript/Value.hs b/src/SAWScript/Value.hs
index c4ef2ec22a..de846bb81e 100644
--- a/src/SAWScript/Value.hs
+++ b/src/SAWScript/Value.hs
@@ -409,6 +409,7 @@ data TopLevelRW =
   , rwProfilingFile :: Maybe FilePath
   , rwLaxArith :: Bool
   , rwWhat4HashConsing :: Bool
+  , rwPreservedRegs :: [String]
   }
 
 newtype TopLevel a =