diff --git a/llvm/cmake/modules/FindZ3.cmake b/llvm/cmake/modules/FindZ3.cmake
--- a/llvm/cmake/modules/FindZ3.cmake
+++ b/llvm/cmake/modules/FindZ3.cmake
@@ -37,7 +37,7 @@
     RUN_OUTPUT_VARIABLE SRC_OUTPUT
   )
 
-  if(Z3_COMPILED)
+  if(Z3_COMPILED AND NOT (Z3_RETURNCODE STREQUAL FAILED_TO_RUN))
     string(REGEX REPLACE "([0-9]*\\.[0-9]*\\.[0-9]*)" "\\1"
            z3_version "${SRC_OUTPUT}")
     set(Z3_VERSION_STRING ${z3_version} PARENT_SCOPE)
@@ -82,25 +82,23 @@
 
 # If the dynamic check fails, we might be cross compiling: if that's the case,
 # check the version in the headers, otherwise, fail with a message
-if(NOT Z3_VERSION_STRING AND (CMAKE_CROSSCOMPILING AND
-                              Z3_INCLUDE_DIR AND
-                              EXISTS "${Z3_INCLUDE_DIR}/z3_version.h"))
+if(NOT Z3_VERSION_STRING AND (Z3_INCLUDE_DIR AND EXISTS "${Z3_INCLUDE_DIR}/z3_version.h"))
   # TODO: print message warning that we couldn't find a compatible lib?
 
   # Z3 4.8.1+ has the version is in a public header.
   file(STRINGS "${Z3_INCLUDE_DIR}/z3_version.h"
        z3_version_str REGEX "^#define[\t ]+Z3_MAJOR_VERSION[\t ]+.*")
-  string(REGEX REPLACE "^.*Z3_MAJOR_VERSION[\t ]+([0-9]).*$" "\\1"
+  string(REGEX REPLACE "^.*Z3_MAJOR_VERSION[\t ]+([0-9]+).*$" "\\1"
          Z3_MAJOR "${z3_version_str}")
 
   file(STRINGS "${Z3_INCLUDE_DIR}/z3_version.h"
        z3_version_str REGEX "^#define[\t ]+Z3_MINOR_VERSION[\t ]+.*")
-  string(REGEX REPLACE "^.*Z3_MINOR_VERSION[\t ]+([0-9]).*$" "\\1"
+  string(REGEX REPLACE "^.*Z3_MINOR_VERSION[\t ]+([0-9]+).*$" "\\1"
          Z3_MINOR "${z3_version_str}")
 
   file(STRINGS "${Z3_INCLUDE_DIR}/z3_version.h"
        z3_version_str REGEX "^#define[\t ]+Z3_BUILD_NUMBER[\t ]+.*")
-  string(REGEX REPLACE "^.*Z3_BUILD_NUMBER[\t ]+([0-9]).*$" "\\1"
+  string(REGEX REPLACE "^.*Z3_BUILD_NUMBER[\t ]+([0-9]+).*$" "\\1"
          Z3_BUILD "${z3_version_str}")
 
   set(Z3_VERSION_STRING ${Z3_MAJOR}.${Z3_MINOR}.${Z3_BUILD})
@@ -122,4 +120,4 @@
                                   REQUIRED_VARS Z3_LIBRARIES Z3_INCLUDE_DIR
                                   VERSION_VAR Z3_VERSION_STRING)
 
-mark_as_advanced(Z3_INCLUDE_DIR Z3_LIBRARIES)
+mark_as_advanced(Z3_INCLUDE_DIR Z3_LIBRARIES)
\ No newline at end of file