diff --git a/CMakeLists.txt b/CMakeLists.txt
index 49bc165d..cce472db 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,6 +13,9 @@ set(OPENEXR_VERSION_API ${OPENEXR_VERSION_MAJOR}_${OPENEXR_VERSION_MINOR})
 
 project(OpenEXR VERSION ${OPENEXR_VERSION})
 
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
+#set(OPENEXR_LOCATION ${CMAKE_INSTALL_PREFIX})
+
 #-------------------------------------------------------------------------------
 # The following user options are cached. They are named with the OPENEXR
 # prefix in order that they be grouped together in tools such as ccmake and cmake-gui.
@@ -141,6 +144,15 @@ if(OPENEXR_BUILD_VIEWERS)
   endif()
 endif()
 
+if ((OPENEXR_BUILD_OPENEXR OR OPENEXR_BUILD_PYTHON_LIBS OR OPENEXR_BUILD_VIEWERS) AND NOT(OPENEXR_BUILD_ILMBASE))
+  message(INFO "OPENEXR_BUILD_ILMBASE not requested, searching for installed IlmBase instead")
+  find_package(IlmBase)
+  if (NOT IlmBase_FOUND)
+    message(ERROR "Could not find IlmBase, cannot build dependent libraries.")
+    message(INFO, "Set ILMBASE_LOCATION to location of IlmBase.")
+  endif()
+endif()
+
 # Perform the build
 if(OPENEXR_BUILD_ILMBASE)
     add_subdirectory(IlmBase)
diff --git a/cmake/FindIlmBase.cmake b/cmake/FindIlmBase.cmake
new file mode 100644
index 00000000..3501c1f7
--- /dev/null
+++ b/cmake/FindIlmBase.cmake
@@ -0,0 +1,192 @@
+
+# adapted from FindOpenEXR.cmake in Pixar's USD distro.
+# 
+# The original license is as follows:
+#
+# Copyright 2016 Pixar
+#
+# Licensed under the Apache License, Version 2.0 (the "Apache License")
+# with the following modification; you may not use this file except in
+# compliance with the Apache License and the following modification to it:
+# Section 6. Trademarks. is deleted and replaced with:
+#
+# 6. Trademarks. This License does not grant permission to use the trade
+#    names, trademarks, service marks, or product names of the Licensor
+#    and its affiliates, except as required to comply with Section 4(c) of
+#    the License and to reproduce the content of the NOTICE file.
+#
+# You may obtain a copy of the Apache License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the Apache License with the above modification is
+# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the Apache License for the specific
+# language governing permissions and limitations under the Apache License.
+#
+
+find_path(ILMBASE_INCLUDE_DIR
+    OpenEXR/Iex.h
+
+HINTS
+    "${OPENEXR_LOCATION}"
+    "${ILMBASE_LOCATION}"
+    "$ENV{OPENEXR_LOCATION}"
+    "$ENV{OPENEXR_ROOT}"
+    "$ENV{ILMBASE_LOCATION}"
+    "$ENV{ILMBASE_ROOT}"
+
+PATH_SUFFIXES
+    include/
+
+NO_DEFAULT_PATH
+NO_SYSTEM_ENVIRONMENT_PATH
+
+DOC
+    "IlmBase headers path"
+)
+
+if(ILMBASE_INCLUDE_DIR)
+  set(ilmbase_config_file "${ILMBASE_INCLUDE_DIR}/OpenEXR/OpenEXRConfig.h")
+  if(EXISTS ${ilmbase_config_file})
+      file(STRINGS
+           ${ilmbase_config_file}
+           TMP
+           REGEX "#define OPENEXR_VERSION_STRING.*$")
+      string(REGEX MATCHALL "[0-9.]+" OPENEXR_VERSION ${TMP})
+
+      file(STRINGS
+           ${ilmbase_config_file}
+           TMP
+           REGEX "#define OPENEXR_VERSION_MAJOR.*$")
+      string(REGEX MATCHALL "[0-9]" OPENEXR_MAJOR_VERSION ${TMP})
+
+      file(STRINGS
+           ${ilmbase_config_file}
+           TMP
+           REGEX "#define OPENEXR_VERSION_MINOR.*$")
+      string(REGEX MATCHALL "[0-9]" OPENEXR_MINOR_VERSION ${TMP})
+  endif()
+else()
+    message(WARNING, " IlmBase headers not found")
+endif()
+
+foreach(ILMBASE_LIB
+    Half
+    Iex
+    IexMath
+    Imath
+    IlmThread)
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${ILMBASE_LIB}_LIBRARY
+        NAMES
+            ${ILMBASE_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}
+            ${ILMBASE_LIB}
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+        DOC
+            "OPENEXR's ${ILMBASE_LIB} library path"
+    )
+
+    if(OPENEXR_${ILMBASE_LIB}_LIBRARY)
+        list(APPEND ILMBASE_LIBRARIES ${OPENEXR_${ILMBASE_LIB}_LIBRARY})
+    endif()
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${ILMBASE_LIB}_DEBUG_LIBRARY
+        NAMES
+            ${ILMBASE_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}_d
+            ${ILMBASE_LIB}_d
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+            debug/lib/
+        DOC
+            "OPENEXR's ${ILMBASE_LIB} debug library path"
+    )
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${ILMBASE_LIB}_STATIC_LIBRARY
+        NAMES
+            ${ILMBASE_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}_s
+            ${ILMBASE_LIB}_s
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+        DOC
+            "OPENEXR's ${ILMBASE_LIB} static library path"
+    )
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${ILMBASE_LIB}_STATIC_DEBUG_LIBRARY
+        NAMES
+            ${ILMBASE_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}_s_d
+            ${ILMBASE_LIB}_s_d
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+            debug/lib/
+        DOC
+            "OPENEXR's ${ILMBASE_LIB} static debug library path"
+    )
+
+endforeach(ILMBASE_LIB)
+
+# So #include <half.h> works
+list(APPEND ILMBASE_INCLUDE_DIRS ${ILMBASE_INCLUDE_DIR})
+list(APPEND ILMBASE_INCLUDE_DIRS ${ILMBASE_INCLUDE_DIR}/OpenEXR)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(IlmBase
+    REQUIRED_VARS
+        ILMBASE_INCLUDE_DIR
+        ILMBASE_LIBRARIES
+    VERSION_VAR
+        OPENEXR_VERSION
+)
+
+foreach(ILMBASE_LIB
+    Half
+    Iex
+    IexMath
+    Imath
+    IlmThread)
+
+    if (OPENEXR_${ILMBASE_LIB}_LIBRARY)
+        add_library(IlmBase::${ILMBASE_LIB} SHARED IMPORTED)
+        set_target_properties(IlmBase::${ILMBASE_LIB} PROPERTIES IMPORTED_LOCATION_RELEASE ${OPENEXR_${ILMBASE_LIB}_LIBRARY})
+        set_target_properties(IlmBase::${ILMBASE_LIB} PROPERTIES IMPORTED_LOCATION_DEBUG ${OPENEXR_${ILMBASE_LIB}_DEBUG_LIBRARY})
+        set_target_properties(IlmBase::${ILMBASE_LIB} PROPERTIES MAP_IMPORTED_CONFIG_RELWITHDEBINFO RELEASE)
+        set_property(TARGET   IlmBase::${ILMBASE_LIB} APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${ILMBASE_INCLUDE_DIR})
+        set_property(TARGET   IlmBase::${ILMBASE_LIB} APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${ILMBASE_INCLUDE_DIR}/OpenEXR)
+    endif()
+
+    if (OPENEXR_${ILMBASE_LIB}_STATIC_LIBRARY)
+        add_library(IlmBase::${ILMBASE_LIB}_static SHARED IMPORTED)
+        set_target_properties(IlmBase::${ILMBASE_LIB}_static PROPERTIES IMPORTED_LOCATION_RELEASE ${OPENEXR_${ILMBASE_LIB}_STATIC_LIBRARY})
+        set_target_properties(IlmBase::${ILMBASE_LIB}_static PROPERTIES IMPORTED_LOCATION_DEBUG ${OPENEXR_${ILMBASE_LIB}_STATIC_DEBUG_LIBRARY})
+        set_target_properties(IlmBase::${ILMBASE_LIB}_static PROPERTIES MAP_IMPORTED_CONFIG_RELWITHDEBINFO RELEASE)
+        set_property(TARGET   IlmBase::${ILMBASE_LIB}_static APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${ILMBASE_INCLUDE_DIR})
+        set_property(TARGET   IlmBase::${ILMBASE_LIB}_static APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${ILMBASE_INCLUDE_DIR}/OpenEXR)
+    endif()
+
+    if (NOT OPENEXR_${ILMBASE_LIB}_LIBRARY AND NOT OPENEXR_${ILMBASE_LIB}_STATIC_LIBRARY)
+      message(WARNING, "${ILMBASE_LIB} was not found.")
+    endif()
+
+endforeach()
diff --git a/cmake/FindOpenEXR.cmake b/cmake/FindOpenEXR.cmake
new file mode 100644
index 00000000..edfb0f54
--- /dev/null
+++ b/cmake/FindOpenEXR.cmake
@@ -0,0 +1,198 @@
+
+# adapted from FindOpenEXR.cmake in Pixar's USD distro.
+# 
+# The original license is as follows:
+#
+# Copyright 2016 Pixar
+#
+# Licensed under the Apache License, Version 2.0 (the "Apache License")
+# with the following modification; you may not use this file except in
+# compliance with the Apache License and the following modification to it:
+# Section 6. Trademarks. is deleted and replaced with:
+#
+# 6. Trademarks. This License does not grant permission to use the trade
+#    names, trademarks, service marks, or product names of the Licensor
+#    and its affiliates, except as required to comply with Section 4(c) of
+#    the License and to reproduce the content of the NOTICE file.
+#
+# You may obtain a copy of the Apache License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the Apache License with the above modification is
+# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the Apache License for the specific
+# language governing permissions and limitations under the Apache License.
+#
+
+find_path(OPENEXR_INCLUDE_DIR
+    OpenEXR/ImfHeader.h
+
+HINTS
+    "${OPENEXR_LOCATION}"
+    "${ILMBASE_LOCATION}"
+    "$ENV{OPENEXR_LOCATION}"
+    "$ENV{OPENEXR_ROOT}"
+    "$ENV{ILMBASE_LOCATION}"
+    "$ENV{ILMBASE_ROOT}"
+
+PATH_SUFFIXES
+    include/
+
+NO_DEFAULT_PATH
+NO_SYSTEM_ENVIRONMENT_PATH
+
+DOC
+    "OpenEXR headers path"
+)
+
+if(OPENEXR_INCLUDE_DIR)
+  set(openexr_config_file "${OPENEXR_INCLUDE_DIR}/OpenEXR/OpenEXRConfig.h")
+  if(EXISTS ${openexr_config_file})
+      file(STRINGS
+           ${openexr_config_file}
+           TMP
+           REGEX "#define OPENEXR_VERSION_STRING.*$")
+      string(REGEX MATCHALL "[0-9.]+" OPENEXR_VERSION ${TMP})
+
+      file(STRINGS
+           ${openexr_config_file}
+           TMP
+           REGEX "#define OPENEXR_VERSION_MAJOR.*$")
+      string(REGEX MATCHALL "[0-9]" OPENEXR_MAJOR_VERSION ${TMP})
+
+      file(STRINGS
+           ${openexr_config_file}
+           TMP
+           REGEX "#define OPENEXR_VERSION_MINOR.*$")
+      string(REGEX MATCHALL "[0-9]" OPENEXR_MINOR_VERSION ${TMP})
+  endif()
+else()
+    message(WARNING, " OpenEXR headers not found")
+endif()
+
+foreach(OPENEXR_LIB
+    IlmImf
+    IlmImfUtil)
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${OPENEXR_LIB}_LIBRARY
+        NAMES
+            ${OPENEXR_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}
+            ${OPENEXR_LIB}
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+        NO_DEFAULT_PATH
+        NO_SYSTEM_ENVIRONMENT_PATH
+        DOC
+            "OPENEXR's ${OPENEXR_LIB} library path"
+    )
+    #mark_as_advanced(OPENEXR_${OPENEXR_LIB}_LIBRARY)
+
+    if(OPENEXR_${OPENEXR_LIB}_LIBRARY)
+        list(APPEND OPENEXR_LIBRARIES ${OPENEXR_${OPENEXR_LIB}_LIBRARY})
+    endif()
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${OPENEXR_LIB}_DEBUG_LIBRARY
+        NAMES
+            ${OPENEXR_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}_d
+            ${OPENEXR_LIB}_d
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+            debug/lib/
+        NO_DEFAULT_PATH
+        NO_SYSTEM_ENVIRONMENT_PATH
+        DOC
+            "OPENEXR's ${OPENEXR_LIB} debug library path"
+    )
+    #mark_as_advanced(OPENEXR_${OPENEXR_LIB}_DEBUG_LIBRARY)
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${OPENEXR_LIB}_STATIC_LIBRARY
+        NAMES
+            ${OPENEXR_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}_s
+            ${OPENEXR_LIB}_s
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+        NO_DEFAULT_PATH
+        NO_SYSTEM_ENVIRONMENT_PATH
+        DOC
+            "OPENEXR's ${OPENEXR_LIB} static library path"
+    )
+    #mark_as_advanced(OPENEXR_${OPENEXR_LIB}_STATIC_LIBRARY)
+
+    # OpenEXR libraries may be suffixed with the version number, so we search
+    # using both versioned and unversioned names.
+    find_library(OPENEXR_${OPENEXR_LIB}_STATIC_DEBUG_LIBRARY
+        NAMES
+            ${OPENEXR_LIB}-${OPENEXR_MAJOR_VERSION}_${OPENEXR_MINOR_VERSION}_s_d
+            ${OPENEXR_LIB}_s_d
+        HINTS
+            "${OPENEXR_LOCATION}"
+            "$ENV{OPENEXR_LOCATION}"
+        PATH_SUFFIXES
+            lib/
+            debug/lib/
+        NO_DEFAULT_PATH
+        NO_SYSTEM_ENVIRONMENT_PATH
+        DOC
+            "OPENEXR's ${OPENEXR_LIB} static debug library path"
+    )
+    #mark_as_advanced(OPENEXR_${OPENEXR_LIB}_STATIC_DEBUG_LIBRARY)
+
+endforeach(OPENEXR_LIB)
+
+# So #include <half.h> works
+list(APPEND OPENEXR_INCLUDE_DIRS ${OPENEXR_INCLUDE_DIR})
+list(APPEND OPENEXR_INCLUDE_DIRS ${OPENEXR_INCLUDE_DIR}/OpenEXR)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(OpenEXR
+    REQUIRED_VARS
+        OPENEXR_INCLUDE_DIRS
+        OPENEXR_LIBRARIES
+    VERSION_VAR
+        OPENEXR_VERSION
+)
+
+foreach(OPENEXR_LIB
+    IlmImf
+    IlmImfUtil)
+
+    if (OPENEXR_${OPENEXR_LIB}_LIBRARY)
+      add_library(OpenEXR::${OPENEXR_LIB} SHARED IMPORTED)
+      set_target_properties(OpenEXR::${OPENEXR_LIB} PROPERTIES IMPORTED_LOCATION_RELEASE ${OPENEXR_${OPENEXR_LIB}_LIBRARY})
+      set_target_properties(OpenEXR::${OPENEXR_LIB} PROPERTIES IMPORTED_LOCATION_DEBUG ${OPENEXR_${OPENEXR_LIB}_DEBUG_LIBRARY})
+      set_target_properties(OpenEXR::${OPENEXR_LIB} PROPERTIES MAP_IMPORTED_CONFIG_RELWITHDEBINFO RELEASE)
+      set_property(TARGET   OpenEXR::${OPENEXR_LIB} APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${OPENEXR_INCLUDE_DIR})
+      set_property(TARGET   OpenEXR::${OPENEXR_LIB} APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${OPENEXR_INCLUDE_DIR}/OpenEXR)
+    endif()
+
+    if (OPENEXR_${OPENEXR_LIB}_STATIC_LIBRARY)
+      add_library(OpenEXR::${OPENEXR_LIB}_static SHARED IMPORTED)
+      set_target_properties(OpenEXR::${OPENEXR_LIB}_static PROPERTIES IMPORTED_LOCATION_RELEASE ${OPENEXR_${OPENEXR_LIB}_STATIC_LIBRARY})
+      set_target_properties(OpenEXR::${OPENEXR_LIB}_static PROPERTIES IMPORTED_LOCATION_DEBUG ${OPENEXR_${OPENEXR_LIB}_STATIC_DEBUG_LIBRARY})
+      set_target_properties(OpenEXR::${OPENEXR_LIB}_static PROPERTIES MAP_IMPORTED_CONFIG_RELWITHDEBINFO RELEASE)
+      set_property(TARGET   OpenEXR::${OPENEXR_LIB}_static APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${OPENEXR_INCLUDE_DIR})
+      set_property(TARGET   OpenEXR::${OPENEXR_LIB}_static APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${OPENEXR_INCLUDE_DIR}/OpenEXR)
+    endif()
+
+    if (NOT OPENEXR_${OPENEXR_LIB}_LIBRARY AND NOT OPENEXR_${OPENEXR_LIB}_STATIC_LIBRARY)
+      message(WARNING, "${OPENEXR_LIB} was not found.")
+    endif()
+
+endforeach()